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We used social network analysis (SNA) to study the novel coronavirus (COVID-19) outbreak in Karnataka, India, and to assess the potential of SNA as a tool for outbreak monitoring and control. We analysed contact tracing data of 1147 COVID-19 positive cases (mean age 34.91 years, 61.99% aged 11–40, 742 males), anonymised and made public by the Karnataka government. Software tools, Cytoscape and Gephi, were used to create SNA graphics and determine network attributes of nodes (cases) and edges (directed links from source to target patients). Outdegree was 1–47 for 199 (17.35%) nodes, and betweenness, 0.5–87 for 89 (7.76%) nodes. Men had higher mean outdegree and women, higher mean betweenness. Delhi was the exogenous source of 17.44% cases. Bangalore city had the highest caseload in the state (229, 20%), but comparatively low cluster formation. Thirty-four (2.96%) ‘super-spreaders’ (outdegree ⩾ 5) caused 60% of the transmissions. Real-time social network visualisation can allow healthcare administrators to flag evolving hotspots and pinpoint key actors in transmission. Prioritising these areas and individuals for rigorous containment could help minimise resource outlay and potentially achieve a significant reduction in COVID-19 transmission.
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Epidemiology and Infection
Original Paper
*Formerly with Department of Community
Medicine, Bangalore Medical College and
Research Institute, Bangalore, Karnataka,
Formerly with Henry Ford Health System,
Detroit, Michigan, USA.
Cite this article: Saraswathi S, Mukhopadhyay
A, Shah H, Ranganath TS (2020). Social
network analysis of COVID-19 transmission in
Karnataka, India. Epidemiology and Infection
148, e230, 110.
Received: 8 June 2020
Revised: 5 September 2020
Accepted: 18 September 2020
Key words:
Analysis of data; contact tracing; COVID-19;
infectious disease epidemiology; social
network analysis
Author for correspondence:
A. Mukhopadhyay,
© The Author(s), 2020. Published by
Cambridge University Press. This is an Open
Access article, distributed under the terms of
the Creative Commons Attribution-
NonCommercial-NoDerivatives licence (http://,
which permits non-commercial re-use,
distribution, and reproduction in any medium,
provided the original work is unaltered and is
properly cited. The written permission of
Cambridge University Press must be obtained
for commercial re-use or in order to create a
derivative work.
Social network analysis of COVID-19
transmission in Karnataka, India
S. Saraswathi1, A. Mukhopadhyay2,*, H. Shah2,and T. S. Ranganath1
Department of Community Medicine, Bangalore Medical College and Research Institute, Bangalore, Karnataka,
India and
Independent researcher
We used social network analysis (SNA) to study the novel coronavirus (COVID-19) outbreak in
Karnataka, India, and to assess the potential of SNA as a tool for outbreak monitoring and con-
trol. We analysed contact tracing data of 1147 COVID-19 positive cases (mean age 34.91 years,
61.99% aged 1140, 742 males), anonymised and made public by the Karnataka government.
Software tools, Cytoscape and Gephi, were used to create SNA graphics and determine network
attributes of nodes (cases) and edges (directed links from source to target patients). Outdegree
was 147 for 199 (17.35%) nodes, and betweenness, 0.587 for 89 (7.76%) nodes. Men had
higher mean outdegree and women, higher mean betweenness. Delhi was the exogenous source
of 17.44% cases. Bangalore city had the highest caseload in the state (229, 20%), but compara-
tively low cluster formation. Thirty-four (2.96%) super-spreaders(outdegree 5) caused 60%
of the transmissions. Real-time social network visualisation can allow healthcare administrators
to flag evolving hotspots and pinpoint key actors in transmission. Prioritising these areas and
individuals for rigorous containment could help minimise resource outlay and potentially
achieve a significant reduction in COVID-19 transmission.
The novel coronavirus (COVID-19) outbreak has attained the proportions of a global calamity. Not
only has the virus sickened millions, it has also affected economic growth worldwide. Researchers
have pointed to overpopulation, globalisation, and hyper-connectivity as factors responsible for
intensifying the spread of infection, turning the outbreak into a pandemic [1]. The first case of cor-
onavirus disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in
India was reported on 30 January 2020, and the first case in Karnataka, a southern state of India, was
reported on 9 March 2020 [2]. In the initial phases of the infections spread through the country,
Karnataka reported fewer cases than other Indian states. It was among the earliest states to deploy
modern technology tools as part of its logistics and containment measures [3,4]. As of 17 May 2020,
Karnataka had declared 1147 diagnosed cases and 18 648 individuals underobservation [5]. Among
the 1147, there were 600 active cases, 509 who had recovered and 37 who died due to COVID (a
fatality rate of 3.2%); one person died by suicide after being diagnosed.
Researchers from several countries have used mathematical modelling to predict the trans-
mission of COVID-19 [68] and to identify predictors of mortality [9,10]. However, social
network analysis (SNA) has not, thus far, been optimally utilised in the endeavour to under-
stand the characteristics of this disease.
SNA is a technique to study the configurations of social relations between individuals or
other social units. Social network models can be used to measure variables that shape relation-
ships between social actors and the extent to which they affect health-related outcomes
[11,12]. Researchers are exploring the use of SNA to study various facets of the COVID-19
pandemic, such as the role of public figures in communication [13], and clustering patterns
within the broader patient network [14].
Since the pandemic is imposing a considerable burden on healthcare delivery systems, any
solution that can potentially aid in controlling its spread deserves serious exploration. One
such approach was the Karnataka healthcare task forces extensive use of contact tracing.
We expanded on this approach by applying SNA to the corpus of contact tracing data gener-
ated by the task forces efforts. We had two main research questions in mind. First, can SNA
improve our understanding of the transmission patterns of SARS-CoV-2? Second, can SNA
produce actionable findings that can help in timely control of the spread of this disease?
Study area
Karnataka is a southern state of India, consisting of 30 administrative districts with a population
of over 60 million, accounting for approximately 5% of the total Indian population. Bangalore, a
densely populated metropolis, is the capital city of Karnataka [15].
Data source
The government of Karnataka initiated measures to control the
spread of COVID-19 in early February 2020 [16]. A government
appointed task force formulated guidelines for quarantine and con-
tact tracing. Field workers, trained to elicit travel and contact his-
tory, carried out telephonic and house-to-house surveys to
identify primary and secondary contacts of positive cases. On aver-
age, 47.4 contacts were tested for each confirmed case [17]. Data
collected at the community level was collated by the State War
Room. Daily consolidated bulletins, containing anonymised patient
and contact data, were uploaded by the government to the portal it
created to share information on COVID-19 [5].
As a part of its effort to contain the outbreak, the Karnataka gov-
ernment implemented a phased lockdown, closing shops and offices,
and shutting down interdistrict and interstate travel. Phase 1 of the
lockdown, with the most stringent curbs on travel and socialisation,
was from 24 March to 14 April. The second phase was from
15 April to 3 May, and the third phase was from 4 May to 17 May.
Study design
For our analysis, we downloaded the daily bulletins containing infor-
mation for all cases reported positive for COVID-19 from 9 March
to 17 May 2020, spanning the period from detection of the first case
in the state to the end of phase-3 of the preventive lockdown. We
extracted relevant demographic and contact data from the bulletins
and created a dataset consisting of anonymised data of 1147
COVID-19 patients. We tabulated and summarised demographic
details such as age, district of residence and history of travel, using
Microsoft Excel. We created a nodes and edges datasheet in Excel,
with each node representing a patient and each edge, a confirmed
link or contact between a source and a target patient. We imported
this dataset into Gephi version 0.9.2 and applied the following sequence
of layout algorithms: Yifan Hu Proportional, Fruchterman Reingold
and No Overlap, to achieve a visual representation in which the
more connected nodes are placed centrally, and ones with lower con-
nectivity are placed towards the periphery of the network [18].
We wanted to combine the capabilities of two of the leading SNA
software tools [19], Gephi and Cytoscape, and utilise the features
missing in one but available in the other. The use of Gephisnetwork
analysis tools results in the nodes and edges datasheet being popu-
lated with additional attribute variables. These values, such as node
betweenness and edge betweenness, can then be displayed as visual
features of the network elements in other software tools such as
Cytoscape [20]. We reformatted the data exported from Gephi to
make it compatible with the data model acceptable to Cytoscape ver-
sion 3.8.0, which we used to create network graphics highlighting
pertinent demographic characteristics of the nodes. Layout algo-
rithms provided in Cytoscape were applied in the following sequence:
Compound Spring Embedder (CoSE) and yFiles Remove Overlap,
followed by a few manual adjustments to improve clarity.
We analysed the network attributes generated by Gephi using
MS Excel to explain relevant aspects of the network and its com-
ponents. We discussed the characteristics and evolution of the
graphs and attempted to explain them in the context of facts
and events on the ground.
Ethical considerations
We have used anonymised, secondary data in the public domain,
available at the COVID-19 information portal of the Karnataka
state government, the copyright policy of which indicates that
material featured on the site may be reproduced free of charge
in any format or media without requiring specific permission,
subject to acknowledgement of the source [5]. The authors assert
that all procedures contributing to this work comply with the eth-
ical standards of the relevant national and institutional commit-
tees, and with the Helsinki Declaration of 1975, as revised in 2008.
Important definitions
(Also displayed in Supplementary Table S1):
Degree centrality is a measure of the number of social connec-
tions or links that a node has. It is expressed as an integer or
count [21].
The indegree of a node is the number of incoming links to it from
source nodes and refers to the number of infectious patients
who had confirmed contact with a given target patient.
Outdegree is the number of links to target nodes from a source
node and is a measure of the number of secondary cases
infected by a given patient. The direction of the links is denoted
by arrowheads at the target ends, in our visual representations.
Betweenness centrality is a measure of the number of times a node
appears on the shortest path between other nodes [22]. It
reflects the role a patient plays in creating a bridge of infectious
transmission between patients who would not have had direct
contact with each other.
Closeness centrality is the average of the shortest path lengths from
a node to every other node in the network. It is calculated as
the inverted sum of the distances from the node to all other
nodes [23].
We used harmonic closeness to measure closeness centrality, due to
the presence of unconnected nodes in our network. It is calculated
as the sum of the inverted distances from a node to all other
nodes, instead of the reciprocal of the sum of all distances [23].
Edge betweenness is the number of the shortest paths that go
through an edge in a graph or network, with a high score indi-
cative of a bridge-like connection between two parts of a net-
work, crucial to transmission between many pairs of nodes [24].
Clustering coefficient measures the degree to which nodes in a
graph tend to cluster together [25].
Network density is the number of existing ties between nodes,
divided by the number of possible ties [26].
Network diameter is the shortest path between the two most dis-
tant nodes in a network [25].
Mean path length is the average of the shortest path lengths
between all possible node pairs [25].
Network component is an island of interlinked nodes that are dis-
connected from other nodes of the network. Many networks
consist of one large component, sometimes together with sev-
eral smaller ones and singleton actors [12].
Super-spreader (operational definition): Any node with an outde-
gree 5 was considered a super-spreader. Individuals repre-
sented by these nodes would have infected five or more contacts.
We analysed 1147 patients of whom 742 (64.69%) were males, aged
34.91 years on average (standard deviation 17.34 years) (Fig. 1).
Most of these individuals (711/1147; 61.99%) belonged to the
2 S. Saraswathi et al.
1140 years age range. Most deaths, however, occurred among
older patients. We observed maximum mortality in patients aged
over 70 years. There were 34 patients in this age-group, of whom
10 (29.41%) had died. Further socio-demographical details of
these patients are available in the public domain [27].
Network parameters
We found 948 nodes with zero outdegree. The remaining 199
(17.35%) nodes had an outdegree range of 147 and were the source
of infection to 657 targets through 706 links (edges). Among the tar-
get nodes, 36 had indegree >1 (range 25), implying more than one
source. We noted equal means, but widely differing standard devia-
tions for outdegree and indegree centralities. This difference is due
to the wider range of outdegree compared to indegree (Table 1).
There were 490 nodes with zero indegree, of which 383 had
zero outdegree. The latter were isolated nodes, with degree cen-
trality value of zero.
The range of betweenness centrality was 0.587 for 89 (7.76%)
nodes. The network had 143 nodes with a harmonic closeness
centrality (HCC) of one, and 56 nodes with HCC between zero
and one. Our network density was 0.001, network diameter was
4 and the clustering coefficient was 0.004.
Table 2 shows that men had a higher mean outdegree (0.628,
Mvs. 0.593, F) and women, higher mean betweenness (0.573, F
vs. 0.412, M).
The 95th percentile cut-off values for outdegree and between-
ness were 3 and 2, respectively. There were 77 (6.71% of 1147)
nodes with outdegree 3, and combined, they accounted for 556
(78.75% of 706) edges. More than two-thirds of these 77 nodes
were men (54, 70.13%). The average HCC for the 77 nodes with
outdegree 3 was 0.887, compared to 0.161 for the entire network.
Of the 59 nodes with betweenness 2, more than half (33, 55.93%)
were men, though women had a higher mean betweenness overall.
We noted 34 super-spreaders with outdegree 5, with a cumu-
lative outdegree of 410, and after deducting 17 duplicate edges for
target nodes with indegree >1, they accounted for 393 (59.81%) of
the 657 target cases.
The aggregate network graphic (Fig. 2), created using Gephi,
shows nodes representing patients, and components representing
case clusters. The nodes are coloured according to district and
sized by outdegree, making the larger nodes represent individuals
who infected a greater number of targets. The largest node, located
at the centre of a major component, denotes a patient from Mysuru
district who infected 47 target nodes. Transmission between districts
was limited, occurring chiefly from Mysuru to Mandya, a geograph-
ically adjacent district. The network figure also has two large-sized
grey nodes that represent two patients with outdegree 29 and 25,
from districts Vijayapura and Uttara Kannada, respectively.
Bangalore had the highest number of cases, followed by Belagavi,
Kalaburagi and Mysuru districts (Supplementary Table S2).
The aggregate network contained 93 clusters of connected
nodes (components), of which 37 components, made up of five
or more nodes each, had more than half of all the nodes (613,
53.44%) and four-fifths of the edges (611, 86.54%) concentrated
within them (Fig. 3). The distribution of these clusters by district
and type of origin is shown in Supplementary Table S3.
Figure 4 shows nodes coloured by age group and sized by out-
degree. Figure 5 shows nodes coloured by source of infection and
sized by betweenness centrality. We have considered patients with
a history of travel from Delhi in a separate category as their count
was comparable to the combined number of travellers from all
other states of India. It is noteworthy that travellers from abroad
did not contribute to the formation of any major cluster.
Fig. 1. Agesex distribution of cases and deaths. Case counts are inclusive of deaths. Death counts are also shown separately.
Epidemiology and Infection 3
Comparing Figures 4(nodes sized by outdegree) and 5(nodes
sized by betweenness), we find that in clusters with nodes that had
multiple interconnections, relatively low outdegree and high
betweenness, the key nodes were females. This indicates that
women played a significant bridging role in these clusters. This
differs from clusters with edges radiating from a central node
with high outdegree and low betweenness, where typically, a
young male was the nidus. The largest and second-largest compo-
nents illustrate this difference in transmission (Fig. 6). The largest
component had 75 nodes and 76 edges, and the second-largest
component had 45 nodes and 50 edges. The largest cluster origi-
nated in the district of Mysuru; its source node was a male with
high outdegree who spread the infection to many contacts.
However, secondary transmission from those contacts was lim-
ited. This cluster is star shaped. The second-largest component
resembles a spiderweb with multiple interconnected nodes and
many female actors. This cluster was in Belagavi, and its network
density was nearly twice that of the largest cluster (0.025 vs.
0.014), with a shorter average path length (1.314 vs. 1.321).
Dynamic evolution of the network
Figure 7 shows how the network began with the first detected
cases and how it expanded in each phase of the lockdown. We
Table 1. Network parameters
Network C1 C2
Nodes 1147 75 45
Edges 706 76 50
Node attributes Range Mean (S.D.) Range (mean)
Outdegree 047 0.616 (2.78) 047 (1.013) 015 (1.111)
Indegree 05 0.616 (0.60) 02 (1.013) 03 (1.111)
Degree 047 1.231 (2.79) 147 (2.027) 115 (2.222)
Betweenness 087 0.469 (3.69) 09 (0.426) 012 (1.133)
Harmonic closeness 1 (n= 143)
0.161 (0.35) 01 (0.231) 01 (0.263)
0<HC<1 (n= 56)
0(n= 949)
Eccentricity 04 0.242 (0.61) 03 (0.307) 03 (0.4)
Network attributes Value
Diameter 4 3 3
Radius 1 1 1
Mean path length 1.623 1.321 1.314
Mean no. of neighbours 1.231 2.027 2.222
Density 0.001 0.025 0.014
Clustering coefficient 0.004 0.011 0.000
C1, largest component; C2, second-largest component; S.D., standard deviation; HC, harmonic closeness.
Table 2. Mean outdegree and betweenness by sex and age group
Age groups
Mean outdegree Mean betweenness
Women Men Combined Women Men Combined
010 0.000 0.140 0.079 0.000 0.233 0.132
1120 0.463 0.368 0.407 0.179 0.242 0.216
2130 0.655 0.289 0.396 1.561 0.095 0.527
3140 0.500 0.994 0.822 0.114 1.159 0.795
4150 0.870 0.480 0.601 0.783 0.216 0.392
5160 1.158 1.145 1.150 0.474 0.210 0.310
6170 0.467 1.083 0.846 0.033 0.406 0.263
7199 0.667 1.263 1.000 1.572 0.000 0.694
Combined 0.593 0.628 0.616 0.573 0.412 0.469
4 S. Saraswathi et al.
Fig. 2. Aggregate network graphic created in Gephi. Arrowheads indicate direction of transmission from source node to target node. Node size determined by
outdegree. Edges inherit colour from parent nodes.
Fig. 3. Major network components organised by size, created in Cytoscape. Arrowheads indicate direction of transmission from source node to target node. Edge
betweenness determines the thickness and colour intensity of the edges.
Epidemiology and Infection 5
see that in the initial, pre-lockdown phase, the cases were mostly
isolated nodes with minimal occurrence of secondary cases. They
are all travellers returning from abroad (red nodes, source type
International Travel). By the time the first and strictest phase
of the lockdown (24 March to 14 April) was declared, however,
cluster formation had already begun and most of the new cases
had a history of travel to Delhi or contact with returnees from
Delhi (green nodes, source type Delhi Hotspot). The origin of
the largest cluster, which was labelled as a Karnataka (in-state)
hotspot (blue nodes), could not be traced either to travel or
to contact with any known positive case. Clusters continued to
form and grow during the second phase of the lockdown (15
April to 3 May). However, due to continuing curbs on travel
and transportation, the fresh cases were mostly found among con-
tacts of existing cases. In the beginning of May 2020, the govern-
ment arranged special transportation facilities by road and rail, so
that migrant labourers in distress could return to their home
states. This resulted in many new cases with source traced to tra-
vel from out of state (orange nodes) in phase 3 of the lockdown (4
May to 17 May). We have shown the weekly increase in cases in
the form of a line graph in Supplementary Figure S1.
While we have performed a basic conventional analysis of the
data, our chief objectives were to create social network graphics
from the empirical contact tracing data, and derive insights into
disease transmission therefrom.
Our study reveals that most cases of COVID-19 in Karnataka
were young and middle-aged men. Deaths, however, occurred
overwhelmingly among elderly patients. The age and sex profile
of our study set matches nationwide surveillance data from
India, with median age and age-distribution close to our sample,
and a similar high attack rate in males [17].
Bangalore, the capital of Karnataka, is a densely populated
metropolis, housing one-sixth of Karnatakas population in 1%
of its area [15,28]. The city airport is a major transit point for
domestic and international travellers. These factors may explain
Bangalores relatively heavy burden of COVID-19 cases (229/
1147). Despite accounting for nearly a fifth of the states caseload,
however, Bangalore did not have notably large or numerous clus-
ters compared to other districts (Fig. 2 and Supplementary Tables
S2 and S3). Most of the cases detected here were isolated nodes.
Bangalores low transmission may have been due to the disci-
plined observance of lockdown measures, and rigorous con-
tact tracing and quarantine activities by its healthcare workforce
The presence of two large nodes (where size denotes outde-
gree) in districts that had a minor contribution to the total case-
load (Fig. 2) points to the risk of cluster formation even in
relatively unaffected areas if, for example, physical distancing
measures are not followed scrupulously.
Fig. 4. Agesex attributes of nodes and clusters, created in Cytoscape. Node size determined by outdegree. Arrowheads indicate direction of transmission from
source node to target node. Edge betweenness determines the thickness and colour intensity of the edges.
6 S. Saraswathi et al.
Shortly after the World Health Organization confirmed the
novel coronavirus as the cause of the outbreak in China [31], pub-
lic health authorities started precautionary screening and quaran-
tine of passengers arriving from areas of concern at Bangalore
International Airport [32]. These early steps may explain why
we found no major clusters originating from international
travellers. Conversely, we noted several clusters formed by people
with a history of travel to the national capital, Delhi (Fig. 5 and
Supplementary Tables S2 and S3). By 19 April 2020, the entire
city of Delhi had been declared a COVID-19 hotspot [33]in
the wake of a mass religious gathering that was found to be linked
to nearly a third of the countrys caseload earlier in the month
Fig. 5. Network analysis by sources of infection (Cytoscape). Node size determined by betweenness. Arrowheads indicate direction of transmission from source
node to target node. Edge betweenness determines the thickness and colour intensity of the edges.
Fig. 6. Comparing the two largest components
(Cytoscape). Node size determined by betweenness.
Arrowheads indicate direction of transmission from
source node to target node. Edge betweenness deter-
mines the thickness and colour intensity of the edges.
Epidemiology and Infection 7
[34]. Clusters of cases that originated from Delhi tended to be
closely interconnected, with women playing an active transmis-
sion role. This could reflect close community ties between these
individuals, or residence in underprivileged areas where strict
physical distancing may not have been observed.
Most of the clusters in our network had a man with high out-
degree as the nidus. Women, however, played an important role in
transmission by bridging multiple nodes within clusters even
though men outnumbered women in the 95th percentile region
of betweenness. Further study is warranted into the social and
behavioural characteristics of men and women that drive these
The low density of our network, the presence of 948 nodes
with zero outdegree, and the fact that only 34 source cases had
infected close to two-thirds of all target cases, indicate that com-
munity transmission was negligible. A similar transmission pat-
tern was reported from Shenzhen, China, where 8.9% of the
cases had caused 80% of all infections [35]. Another recent
analysis of detailed contact tracing data from Hunan, China,
traced 80% of secondary cases back to 14% of infections [36].
Network analysis of COVID-19 patients in Henan, China, [14]
revealed a non-uniform pattern of clustering (208/1105 patients
in clusters) with a skewed distribution of patients in different cit-
ies. The Henan study also indicated a strong correlation of con-
firmed cases with travel to Wuhan (the epicentre of the
pandemic), which corresponds to our observation that a fair pro-
portion (17.44%) of the Karnataka patients had travelled to Delhi.
These similarities indicate that our findings may be generalisable
across populations.
Researchers have analysed network properties from different
perspectives, depending on the type and complexity of networks.
Entropy-based analysis has been used to identify influential nodes
using local information dimensionality [37]. Fractal dimensions
are being explored to determine the vulnerability of complex net-
works [38]. Mathematical modelling has been used to simulate
and predict transmission dynamics in various types of networks
Fig. 7. Evolution of the network at each phase of lockdown. Node colour denotes infection source type. Arrowheads indicate direction of transmission from source
node to target node.
8 S. Saraswathi et al.
[39]. These models are informed, and their predictions are influ-
enced, by the types of data processing decisions that are made
prior to collecting and analysing the contact data [40]. A dynamic
simulation of this nature, such as was done by the Hunan
researchers [36], would require data at a granular level, including
educational, occupational and socioeconomic status of patients,
their mobility patterns, severity of infection, and the duration
and intensity of contact events. This information was unavailable
in the anonymised secondary data that we used. The data avail-
able to us allowed only a limited dynamic analysis to be done.
Our SNA findings may not universally reflect field realities. Some
findings such as eccentricity and mean path length are theoretical
constructs computed by software algorithms, but in practice, these
metrics remain indeterminate as our network had very few inter-
district connections and many isolated nodes and components.
Our dataset included many patients with contact history still
under investigation at the time of analysis. We were not able to
analyse the role of type and duration of contact, as these data
were unavailable for many patients. Although we have attempted
to faithfully reproduce all the information that we could extract
from the daily bulletins, the quality of our data is necessarily lim-
ited by the constraints of secondary data sources.
Our conventional analysis indicates that mortality due to
COVID-19 is highest among senior citizens. We recommend
that the elderly should be advised strict physical distancing, and
older patients from rural or underserved areas should be pre-
emptively transferred to tertiary centres with intensive care
facilities. This may help in early detection and treatment of com-
plications, mitigating their mortality risk.
The findings from our network analysis suggest that geograph-
ical, demographical and community characteristics could
influence the spread of COVID-19. Gender influences the morph-
ology of clusters, with men seeding the clusters and women
propagating them.
Our results also highlight the need for recording, on an
ongoing basis, high granularity contact tracing data in a uniform
format. We believe that outbreak control task forces should be
provided with requisite software and training in SNA techniques,
and should directly receive contact tracing information from
workers in the field. This would enable SNA in real time with
the ability to visualise and flag evolving networks with alacrity.
It would also help pinpoint nodes with high outdegree, between-
ness and closeness scores, which imply an active role in the trans-
mission and bridging of infection. Real-time SNA could thus help
identify the super-spreaders responsible for a large proportion of
transmission. In particular, close tracking of betweenness scores
would allow detection of individuals who might be missed by
conventional tracing methods. These actors may not themselves
spread the infection to many contacts, but their bridging charac-
teristic accelerates transmission in the community. Public health
authorities could prioritise these individuals and clusters for
immediate and rigorous containment, and formulate control mea-
sures tailored to the network characteristics of each locality. These
measures could help minimise resource outlay, and potentially
facilitate a significant reduction in the spread of COVID-19.
Supplementary material. The supplementary material for this article can
be found at
Acknowledgements. We thank the Government of Karnataka for their
punctual and detailed bulletins summarising data of COVID-19 cases in the
state. We are deeply grateful to the grassroots health workers who selflessly
carried out the contact tracing surveys that made our analysis possible. We
extend our sincere thanks to the reviewers and the editor for their valuable
suggestions and support.
Author contributions.
S. Saraswathi: conceptualisation, study design, data retrieval from government bulletins;
A. Mukhopadhyay and H. Shah: data analysis; all authors: writing, editing, review and
final approval of manuscript.
Financial support. We received no financial support for this study.
Conflict of interest. We have no conflict of interest to declare.
Data availability statement. Our datasets were constructed using contact
tracing details available in the daily bulletins released online by the
Government of Karnataka. The complete archives of these bulletins can be
accessed at the COVID-19 portal at the address https://covid19.karnataka. under the heading Health Department Bulletins.
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10 S. Saraswathi et al.
... Or, briefly, to how social relationships are organized within society [12,13]. In effect, ideas and statistical models from the network science [14] have already been applied to various topics related to the COVID-19 pandemic, such as the global and local spread of the virus [1,15,16], the exploration of SARS-COV-2 contact tracing data [6,17,18], the assessment of vaccination strategies [19,20], the analysis of vaccine patents [21], the evaluation of distancing strategies [22], etc. ...
... Given this age-homophily effect, children and adolescents were predicted to have the highest incidence, at least during the initial phase of an epidemic. A contact tracing study [37] implemented in South Korea during the COVID-19 outbreak showed that the 3 contacts of symptomatic young people (aged [10][11][12][13][14][15][16][17][18][19] contracted the disease, in households, in 18.6% of cases (a percent larger than any other age group). Moreover, people aged 70 and 79 were the most likely to spread SARS-COV-2 outside the households (4.8% of their non-household contacts became infected). ...
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We analyse officially procured data detailing the COVID-19 transmission in Romania’s capital Bucharest between 1st August and 31st October 2020. We apply relational hyperevent models on 19,713 individuals with 13,377 infection ties to determine to what degree the disease spread is affected by age whilst controlling for other covariate and human-to-human transmission network effects. We find that positive cases are more likely to nominate alters of similar age as their sources of infection, thus providing evidence for age homophily. We also show that the relative infection risk is negatively associated with the age of peers, such that the risk of infection increases as the average age of contacts decreases. Additionally, we find that adults between the ages 35 and 44 are pivotal in the transmission of the disease to other age groups. Our results may contribute to better controlling future COVID-19 waves, and they also point to the key age groups which may be essential for vaccination given their prominent role in the transmission of the virus.
... Even though susceptible people may never have had contact with primary patients, they could establish connections with them through these influential bridging patients and unwittingly become a similar transmission bridge to spread the virus. These actors may not spread the infection to many contacts, but their bridging characteristic accelerates transmission in the community (24). This is particularly the case for cross-community bridges, for example, taxi or ride-hailing drivers who travel around the city. ...
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Background Due to the continual recurrence of COVID-19 in urban areas, it is important to know more about the evolution of the epidemic within this setting to mitigate the risk of the situation getting worse. As the virus spreads through human society, the social networks of confirmed cases can provide us with crucial new insights on this question. Methods Based on the epidemiological reports of 235 COVID-19 cases in Nanjing, we constructed a social contact network for the epidemic. By analyzing the structure of this network, we explored the transmission characteristics of the epidemic, to provide evidence-based explanations for its transmission. Results In our constructed transmission network, more than half (95/165, 57.58%) of patients were found not to have transmitted the infection, with only 15 (9.10%) source patients accounting for more than a third of the contagion (60, 36.36%), suggesting that the transmission of COVID-19 varies per individuals. Patients in the 31 to 50 age group were the main source of infectious clusters, with females playing a more active role in passing on the infection. Network component analysis identified nine components with disproportionate concentrations of influential patients, accounting for 49.09% (81) of the patients and 59.09% (78) of epidemiological network contacts. Family aggregation may favor disease transmission, and parenthood is the relationship with the highest infection risk within the family cluster. In addition, some specific public places, such as chess and card parlors, were found to be notable hotspots for community infection. Conclusion This study presents the evolution of the urban epidemic from the perspective of individual-level and socially interactive processes. This real-world evidence can help to increase public awareness of the epidemic, formulate countermeasures, and allocate limited public health resources for urban management.
... Today, in addition to short-term estimating of the prevalence pattern and assessing the risk of infection with the COVID-19 [10,11], real-time applications are increasing in various fields of medicine, such as the diagnosis of cardiac arrhythmias [12]. Also, the social network analysis [13,14] and the partial correlation coefficients [15] approaches have been used to recognize high-risk areas of the disease and identify effective climatology factors on the prevalence of COVID-19, respectively. As a last attempt, researchers have employed different deep learning methods to distinguish positive cases based on chest X-ray and CT-Scan images [16][17][18][19][20][21][22][23]. ...
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The world today faces a new challenge that is unprecedented in the last 100 years. The emergence of a new coronavirus has led to a human catastrophe. Scientists in various sciences have been looking for solutions to this problem so far. In addition to general vaccination, maintaining social distance and adherence to government guidelines on safety precaution measures are the most well-known strategies to prevent COVID-19 infection. In this research, we tried to examine the symptoms of COVID-19 cases through different supervised machine learning methods. We solved the class imbalance problem using the synthetic minority over-sampling (SMOTE) method and then developed some classification models to predict the outcome of COVID-19 cases (recovery or death). Besides, we implemented a rule-based technique to identify different combinations of variables with specific ranges of their values that together affect disease severity. Our results showed that the random forest model with 95.6% accuracy, 97.1% sensitivity, 94.0% specification, 94.4% precision, 95.8% F-score, and 99.3% AUC-score outperforms state-of-the-art classification models. Finally, we identified the most significant rules that state various combinations of 6 features in certain ranges of their values lead to patients’ recovery with a confidence value of 90%. In conclusion, the classification results in this study show better performance than recent studies, and the extracted rules help physicians consider other important factors in improving health services to different groups of COVID-19 patients.
... A number of studies have examined the effects of mobility reduction on case counts outside of the United States [10,14]. In a comprehensive review focused on the geospatial and spatial-statistical analysis of the pandemic, Franch-Pardo et al. [7] evaluated numerous scientific articles on the subject and concluded that interdisciplinary action, proactive planning, and international solidarity were of utmost importance for controlling the virus. ...
... 11,12 So far, most of the published works that explored transmission networks using contact tracing data have focused on the relationships between individuals to identify superspreaders. 9,13,14 Limited studies were concerned with the macroscopic linkages among multiple transmission clusters, the understanding of which could be important in guiding public health interventions. 15 This article describes an algorithm for constructing a network of transmission clusters from contact tracing data by capturing both temporal and network topological features for social network analysis to identify SARS-CoV-2 clusters of public health importance. ...
Objective: Contact tracing of reported infections could enable close contacts to be identified, tested, and quarantined for controlling further spread. This strategy has been well demonstrated in the surveillance and control of COVID-19 (coronavirus disease 2019) epidemics. This study aims to leverage contact tracing data to investigate the degree of spread and the formation of transmission cascades composing of multiple clusters. Materials and methods: An algorithm on mining relationships between clusters for network analysis is proposed with 3 steps: horizontal edge creation, vertical edge consolidation, and graph reduction. The constructed network was then analyzed with information diffusion metrics and exponential-family random graph modeling. With categorization of clusters by exposure setting, the metrics were compared among cascades to identify associations between exposure settings and their network positions within the cascade using Mann-Whitney U test. Results: Experimental results illustrated that transmission cascades containing or seeded by daily activity clusters spread faster while those containing social activity clusters propagated farther. Cascades involving work or study environments consisted of more clusters, which had a higher transmission range and scale. Social activity clusters were more likely to be connected, whereas both residence and healthcare clusters did not preferentially link to clusters belonging to the same exposure setting. Conclusions: The proposed algorithm could contribute to in-depth epidemiologic investigation of infectious disease transmission to support targeted nonpharmaceutical intervention policies for COVID-19 epidemic control.
... This centrality has been used in many practical problems. Such as, during the current Covid-19 pandemic, the authors in [32] used the BC indicator to identify subjects that need to be localized soon to proactively prevent the spread of SARS-CoV-2 coronavirus. In [13], [19], authors proved that BC has an important influence on the acceptance and diffusion of information. ...
... Network Analysis of Covid-19 infection transmission among different age groups in Karnataka from 9 March to 17 May 2020[32] ...
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Objectives: To apply various data visualization techniques on COVID-19 datasets that help to get insights, make accurate decisions, find trends and patterns, and present valuable information. Methods: The following data visualization techniques, i.e., Bar graph, Box plot, Bubble chart, Choropleth map, Density plot, Heat map, Histogram, Line graph, Network analysis, Parallel coordinates, Pie chart, Scatter plot, Scatter plot matrices, Timeline chart, Time series plot, Tree map, Violin plot, Word cloud are used on various Covid-19 datasets taken from Kaggle. Findings: Analyzing vast volumes of data is a tedious task and practically impossible, and hence data visualization is needed to make those datasets meaningful. There are various types of data like categorical, numerical, spatial, time-series, and many more. For analyzing various types of data, different data visualization techniques are required. On the same data, different techniques provide different insights and different ways of visualization. On COVID-19 data different techniques gave different insights, for instance, density plot gave a clear idea about the distribution of COVID-19 cases, Pie chart about recovery, death, and discharge rate, though box plot and violin plot are drawn using the same data their visualizations are completely different. Every data visualization technique has its own pros and cons, so knowing various techniques is essential. Applications: Data visualization finds its application in each and every industry. This paper discusses how data visualization can be applied to Covid-19 data and how meaningful insights can be drawn.
Coronavirus disease 2019 (COVID-19) has attracted research interests from all fields. Phylogenetic and social network analyses based on connectivity between either COVID-19 patients or geographic regions and similarity between syndrome coronavirus 2 (SARS-CoV-2) sequences provide unique angles to answer public health and pharmaco-biological questions such as relationships between various SARS-CoV-2 mutants, the transmission pathways in a community and the effectiveness of prevention policies. This paper serves as a systematic review of current phylogenetic and social network analyses with applications in COVID-19 research. Challenges in current phylogenetic network analysis on SARS-CoV-2 such as unreliable inferences, sampling bias and batch effects are discussed as well as potential solutions. Social network analysis combined with epidemiology models helps to identify key transmission characteristics and measure the effectiveness of prevention and control strategies. Finally, future new directions of network analysis motivated by COVID-19 data are summarized.
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As the world grapples with the problem of the coronavirus disease 2019 (COVID-19) pandemic and its devastating effects, scientific groups are working towards solutions to mitigate the effects of the virus. This paper aimed to collate information on COVID-19 prediction models. A systematic literature review is reported, based on a manual search of 1,196 papers published from January to December 2020. Various databases such as Google Scholar, Web of Science, and Scopus were searched. The search strategy was formulated and refined in terms of subject keywords, geographical purview, and time period according to a predefined protocol. Visualizations were created to present the data trends according to different parameters. The results of this systematic literature review show that the study findings are critically relevant for both healthcare managers and prediction model developers. Healthcare managers can choose the best prediction model output for their organization or process management. Meanwhile, prediction model developers and managers can identify the lacunae in their models and improve their data-driven approaches.
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A long-standing question in infectious disease dynamics concerns the role of transmission heterogeneities, driven by demography, behavior and interventions. Based on detailed patient and contact tracing data in Hunan, China we find 80% of secondary infections traced back to 15% of SARS-CoV-2 primary infections, indicating substantial transmission heterogeneities. Transmission risk scales positively with the duration of exposure and the closeness of social interactions and is modulated by demographic and clinical factors. The lockdown period increases transmission risk in the family and households, while isolation and quarantine reduce risks across all types of contacts. The reconstructed infectiousness profile of a typical SARS-CoV-2 patient peaks just before symptom presentation. Modeling indicates SARS-CoV-2 control requires the synergistic efforts of case isolation, contact quarantine, and population-level interventions, owing to the specific transmission kinetics of this virus.
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This study aimed to identify clinical features for prognosing mortality risk using machine-learning methods in patients with coronavirus disease 2019 (COVID-19). A retrospective study of the inpatients with COVID-19 admitted from 15 January to 15 March 2020 in Wuhan is reported. The data of symptoms, comorbidity, demographic, vital sign, CT scans results and laboratory test results on admission were collected. Machine-learning methods (Random Forest and XGboost) were used to rank clinical features for mortality risk. Multivariate logistic regression models were applied to identify clinical features with statistical significance. The predictors of mortality were lactate dehydrogenase (LDH), C-reactive protein (CRP) and age based on 500 bootstrapped samples. A multivariate logistic regression model was formed to predict mortality 292 in-sample patients with area under the receiver operating characteristics (AUROC) of 0.9521, which was better than CURB-65 (AUROC of 0.8501) and the machine-learning-based model (AUROC of 0.4530). An out-sample data set of 13 patients was further tested to show our model (AUROC of 0.6061) was also better than CURB-65 (AUROC of 0.4608) and the machine-learning-based model (AUROC of 0.2292). LDH, CRP and age can be used to identify severe patients with COVID-19 on hospital admission.
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In São Paulo, Brazil, the first case of coronavirus disease 2019 (CoViD-19) was confirmed on 26 February, the first death due to CoViD-19 was registered on 16 March, and on 24 March, São Paulo implemented the isolation of persons in non-essential activities. A mathematical model was formulated based on non-linear ordinary differential equations considering young (60 years old or less) and elder (60 years old or more) subpopulations, aiming to describe the introduction and dissemination of the new coronavirus in São Paulo. This deterministic model used the data collected from São Paulo to estimate the model parameters, obtaining R0 = 6.8 for the basic reproduction number. The model also allowed to estimate that 50% of the population of São Paulo was in isolation, which permitted to describe the current epidemiological status. The goal of isolation implemented in São Paulo to control the rapid increase of the new coronavirus epidemic was partially succeeded, concluding that if isolation of at least 80% of the population had been implemented, the collapse in the health care system could be avoided. Nevertheless, the isolated persons must be released one day. Based on this model, we studied the potential epidemiological scenarios of release by varying the proportions of the release of young and elder persons. We also evaluated three different strategies of release: All isolated persons are released simultaneously, two and three releases divided in equal proportions. The better scenarios occurred when young persons are released, but maintaining elder persons isolated for a while. When compared with the epidemic without isolation, all strategies of release did not attain the goal of reducing substantially the number of hospitalisations due to severe CoViD-19. Hence, we concluded that the best decision must be postponing the beginning of the release.
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This study aims to identify the risk factors associated with mortality and survival of COVID-19 cases in a state of the Brazilian Northeast. It is a historical cohort with a secondary database of 2070 people that presented flu-like symptoms, sought health assistance in the state and tested positive to COVID-19 until 14 April 2020, only moderate and severe cases were hospitalised. The main outcome was death as a binary variable (yes/no). It also investigated the main factors related to mortality and survival of the disease. Time since the beginning of symptoms until death/end of the survey (14 April 2020) was the time variable of this study. Mortality was analysed by robust Poisson regression, and survival by Kaplan-Meier and Cox regression. From the 2070 people that tested positive to COVID-19, 131 (6.3%) died and 1939 (93.7%) survived, the overall survival probability was 87.7% from the 24th day of infection. Mortality was enhanced by the variables: elderly (HR 3.6; 95% CI 2.3-5.8; P < 0.001), neurological diseases (HR 3.9; 95% CI 1.9-7.8; P < 0.001), pneumopathies (HR 2.6; 95% CI 1.4-4.7; P < 0.001) and cardiovascular diseases (HR 8.9; 95% CI 5.4-14.5; P < 0.001). In conclusion, mortality by COVID-19 in Ceará is similar to countries with a large number of cases of the disease, although deaths occur later. Elderly people and comorbidities presented a greater risk of death.
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Background & objectives: India has been reporting the cases of coronavirus disease 2019 (COVID-19) since January 30, 2020. The Indian Council of Medical Research (ICMR) formulated and established laboratory surveillance for COVID-19. In this study, an analysis of the surveillance data was done to describe the testing performance and descriptive epidemiology of COVID-19 cases by time, place and person. Methods: The data were extracted from January 22 to April 30, 2020. The frequencies of testing performance were described over time and by place. We described cases by time (epidemic curve by date of specimen collection; seven-day moving average), place (area map) and person (attack rate by age, sex and contact status), and trends were represented along with public health measures and events. Results: Between January 22 and April 30, 2020, a total of 1,021,518 individuals were tested for severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). Testing increased from about 250 individuals per day in the beginning of March to 50,000 specimens per day by the end of April 2020. Overall, 40,184 (3.9%) tests were reported positive. The proportion of positive cases was highest among symptomatic and asymptomatic contacts, 2-3-fold higher than among those with severe acute respiratory infection, or those with an international travel history or healthcare workers. The attack rate (per million) by age was highest among those aged 50-69 yr (63.3) and was lowest among those under 10 yr (6.1). The attack rate was higher among males (41.6) than females (24.3). The secondary attack rate was 6.0 per cent. Overall, 99.0 per cent of 736 districts reported testing and 71.1 per cent reported COVID-19 cases. Interpretation & conclusions: The coverage and frequency of ICMR's laboratory surveillance for SARS-CoV-2 improved over time. COVID-19 was reported from most parts of India, and the attack rate was more among men and the elderly and common among close contacts. Analysis of the data indicates that for further insight, additional surveillance tools and strategies at the national and sub-national levels are needed.
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Objectives This study explores how public key players play an important role in social networks for coronavirus (COVID‐19). Methods This study employs social network analyses based on 2,864 Twitter users and 2,775 communications of Twitter. Results This study finds that President Trump plays the most important role in social networks among the top 20 key players for both in‐degree centrality and content in tweets. Second, Donald Trump and Barak Obama show the opposite result for the in‐degree centrality and follower analysis. The result shows that the topic‐based networks and the person‐based networks play a different role in social networks. This study demonstrates that the presidents, the World Health Organization (WHO) and its regional offices, the Centers for Disease Control, and news channels play a crucial role in the news of COVID‐19 for people. Key players, such as Donald Trump, Barack Obama, and BBC, are located in the central networks. In contrast, U.S. news channels and WHO and its regional offices have independent channels. Conclusions Governments should understand the characteristics of public key players to provide information for COVID‐19 in a timely manner.
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Background Rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Wuhan, China, prompted heightened surveillance in Shenzhen, China. The resulting data provide a rare opportunity to measure key metrics of disease course, transmission, and the impact of control measures. Methods From Jan 14 to Feb 12, 2020, the Shenzhen Center for Disease Control and Prevention identified 391 SARS-CoV-2 cases and 1286 close contacts. We compared cases identified through symptomatic surveillance and contact tracing, and estimated the time from symptom onset to confirmation, isolation, and admission to hospital. We estimated metrics of disease transmission and analysed factors influencing transmission risk. Findings Cases were older than the general population (mean age 45 years) and balanced between males (n=187) and females (n=204). 356 (91%) of 391 cases had mild or moderate clinical severity at initial assessment. As of Feb 22, 2020, three cases had died and 225 had recovered (median time to recovery 21 days; 95% CI 20–22). Cases were isolated on average 4·6 days (95% CI 4·1–5·0) after developing symptoms; contact tracing reduced this by 1·9 days (95% CI 1·1–2·7). Household contacts and those travelling with a case were at higher risk of infection (odds ratio 6·27 [95% CI 1·49–26·33] for household contacts and 7·06 [1·43–34·91] for those travelling with a case) than other close contacts. The household secondary attack rate was 11·2% (95% CI 9·1–13·8), and children were as likely to be infected as adults (infection rate 7·4% in children <10 years vs population average of 6·6%). The observed reproductive number (R) was 0·4 (95% CI 0·3–0·5), with a mean serial interval of 6·3 days (95% CI 5·2–7·6). Interpretation Our data on cases as well as their infected and uninfected close contacts provide key insights into the epidemiology of SARS-CoV-2. This analysis shows that isolation and contact tracing reduce the time during which cases are infectious in the community, thereby reducing the R. The overall impact of isolation and contact tracing, however, is uncertain and highly dependent on the number of asymptomatic cases. Moreover, children are at a similar risk of infection to the general population, although less likely to have severe symptoms; hence they should be considered in analyses of transmission and control. Funding Emergency Response Program of Harbin Institute of Technology, Emergency Response Program of Peng Cheng Laboratory, US Centers for Disease Control and Prevention.
As the world struggles through the COVID-19 pandemic, we should also be asking what systems-level measures will be needed to prevent this or even worse disasters from happening in the future. We argue that the pandemic is merely one of potentially myriad and pleiomorphic future global disasters generated by the same underlying dynamical system. We explain that there are four broad but easily identifiable systemic, pathologically networked conditions that are hurtling civilization toward potential self-destruction. As long as these conditions are not resolved, we should consider catastrophe as an inevitable emergent endpoint from the dynamics. All four conditions can be reversed with collective action to begin creating an enduring and thriving post-COVID-19 world. This will require maximal application of the precautionary principle.
A long-standing question in infectious disease dynamics concerns the role of transmission heterogeneities, driven by demography, behavior and interventions. Based on detailed patient and contact tracing data in Hunan, China we find 80% of secondary infections traced back to 15% of SARS-CoV-2 primary infections, indicating substantial transmission heterogeneities. Transmission risk scales positively with the duration of exposure and the closeness of social interactions and is modulated by demographic and clinical factors. The lockdown period increases transmission risk in the family and households, while isolation and quarantine reduce risks across all types of contacts. The reconstructed infectiousness profile of a typical SARS-CoV-2 patient peaks just before symptom presentation. Modeling indicates SARS-CoV-2 control requires the synergistic efforts of case isolation, contact quarantine, and population-level interventions, owing to the specific transmission kinetics of this virus. One Sentence Summary Public health measures to control SARS-CoV-2 could be designed to block the specific transmission characteristics of the virus.
India has experienced an early and harshest lockdown from 25th March 2020 in response to the outbreak. However, an accurate estimation of the progression of the spread of infection and the level of preparedness to combat this disease are urgently needed. Using a data-based mathematical model, our study has made predictions on the number of cases that are expected to rise in India till 14th June 2020. The epidemiological data of daily cases have been utilized from 25th March (i.e., the first day of lockdown) to 23rd April 2020. In the study, we have stimulated two possible scenarios (optimistic and pessimistic) for the prediction. As per the optimistic approach of modelling, COVID-19 may end in the first week of June 2020 with a total of 77,900 infected cases including 2,442 fatalities. However, the results under the pessimistic scenario are a bit scary as it shows that a total of 283,300 infected cases with 10,180 fatalities till 14th June. To win the battle, 10 weeks of complete lockdown is much needed at least in the infected states and the union territories of India. Alternatively, the isolation of clusters (hotspot regions) is required if India wants a resume of some essential activities.