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Characteristics of and Important Lessons From
the Coronavirus Disease 2019 (COVID-19) Outbreak in China
Summary of a Report of 72 314 Cases From
the Chinese Center for Disease Control and Prevention
The Chinese Center for Disease Control and Preven-
tion recently published the largest case series to date of
coronavirus disease 2019 (COVID-19)in mainland China
(72 314 cases, updated through February 11, 2020).
1
This
Viewpoint summarizes key findings from this report and
discusses emerging understanding of and lessons from
the COVID-19 epidemic.
Epidemiologic Characteristics
of the COVID-19 Outbreak
Among a total of 72 314 case records (Box), 4 4 672
were classified as confirmed cases of COVID-19 (62%;
diagnosis based on positive viral nucleic acid test result
on throat swab samples), 16 186 as suspected cases
(22%; diagnosis based on symptoms and exposures
only, no test was performed because testing capacity is
insufficient to meet current needs), 10 567 as clinically
diagnosed cases (15%; this designation is being used in
Hubei Province only; in these cases, no test was per-
formed but diagnosis was made based on symptoms,
exposures, and presence of lung imaging features con-
sistent with coronavirus pneumonia), and 889 as
asymptomatic cases (1%; diagnosis by positive viral
nucleic acid test result but lacking typical symptoms
including fever, dry cough, and fatigue).
1
Most case patients were 30 to 79 years of age
(87%), 1% were aged 9 years or younger, 1% were aged
10 to 19 years, and 3% were age 80 years or older.
Most cases were diagnosed in Hubei Province (75%)
and most reported Wuhan-related exposures (86%;
ie, Wuhan resident or visitor or close contact with
Wuhan resident or visitor). Most cases were classified
as mild (81%; ie, nonpneumonia and mild pneumonia).
However, 14% were severe (ie, dyspnea, respiratory
frequency ⱖ30/min, blood oxygen saturation ⱕ93%,
partial pressure of arterial oxygen to fraction of inspired
oxygen ratio <300, and/or lung infiltrates >50% within
24 to 48 hours), and 5% were critical (ie, respiratory
failure, septic shock, and/or multiple organ dysfunction
or failure) (Box).
1
The overall case-fatality rate (CFR) was2.3% (1023
deaths among 44 672 confirmed cases). No deaths oc-
curred in the group aged 9 years and younger, but cases
in those aged 70 to 79 years had an 8.0% CFR and
cases in those aged 80 years and older had a 14.8%CFR.
No deaths were reported among mild and severe cases.
The CFR was 49.0% among critical cases. CFR was el-
evated among those with preexisting comorbid condi-
tions—10.5% for cardiovasculardisease, 7.3% for diabe-
tes, 6.3% for chronic respiratory disease, 6.0% for
hypertension, and 5.6% for cancer. Among the 44 672
cases, a total of 1716 were health workers (3.8%), 1080
of whom were in Wuhan (63%). Overall, 14.8% of con-
firmed cases among health workers were classified as
severe or critical and 5 deaths were observed.
1
COVID-19 rapidly spread from a single city to
the entire country in just 30 days. The sheer speed of
both the geographical expansion and the sudden in-
crease in numbers of cases surprised and quickly over-
whelmed health and public health services in China, par-
ticularly in Wuhan City and Hubei Province. Epidemic
curves reflect what may be a mixed outbreak pattern,
with early cases suggestive of a continuous common
source, potentially zoonotic spillover at Huanan Sea-
food Wholesale Market, and later cases suggestive of a
propagated source as the virus began to be transmit-
ted from person to person (Figure 1).
1
Comparison of COVID-19 With SARS and MERS
The current COVID-19 outbreak is both similar and dif-
ferent to the prior severe acute respiratory syndrome
Box. Key Findings Fromthe Chinese Center
for Disease Control and Prevention Report
72 314 Cases (as of February 11, 2020)
•Confirmed cases: 44 672 (62%)
•Suspected cases: 16 186 (22%)
•Diagnosed cases: 10 567 (15%)
•Asymptomatic cases: 889 (1%)
Age distribution (N = 44 672)
•ⱖ80 years: 3% (1408 cases)
•30-79 years: 87% (38680 cases)
•20-29 years: 8% (3619case s)
•10-19 years: 1% (549 cases)
•<10 years: 1% (416 cases)
Spectrum of disease (N = 44 415)
•Mild: 81% (36 160 cases)
•Severe: 14% (6168 cases)
•Critical: 5% (2087 cases)
Case-fatality rate
•2.3% (1023 of 44 672 confirmed cases)
•14.8% in patients aged ⱖ80 years (208 of 1408)
•8.0% in patients aged 70-79 years (312 of 3918)
•49.0% in critical cases (1023 of 2087)
Health care personnel infected
•3.8% (1716 of 44 672)
•63% in Wuhan (1080 of 1716)
•14.8% cases classified as severe or critical
(247 of 1668)
•5 deaths
VIEWPOINT
Zunyou Wu,MD, PhD
Chinese Center for
Disease Control and
Prevention, Beijing,
China.
Jennifer M.
McGoogan, PhD
Chinese Center for
Disease Control and
Prevention, Beijing,
China.
Viewpoint
Related article
Corresponding
Author: Zunyou
Wu, MD, PhD,
Chinese Center
for Disease Control
and Prevention,
155 Changbai Rd,
Beijing 102206, China
(wuzy@263.net).
Opinion
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Figure 1. Epidemic Curve of the Confirmed Cases of Coronavirus Disease 2019 (COVID-19)
Jan 14, 2020
1500
1000
500
4000
3500
3000
2500
2000
0
No. of cases
By date of diagnosis (n
=
44
672)
By date of onset (n
=
44
672)
Confirmed cases only
Feb 11, 2020
Feb 10, 2020
Feb 9, 2020
Feb 8, 2020
Feb 7, 2020
Feb 6, 2020
Feb 5, 2020
Feb 4, 2020
Feb 3, 2020
Feb 2, 2020
Feb 1, 2020
Jan 31, 2020
Jan 30, 2020
Jan 29, 2020
Jan 28, 2020
Jan 27, 2020
Jan 26, 2020
Jan 25, 2020
Jan 24, 2020
Jan 23, 2020
Jan 22, 2020
Jan 21, 2020
Jan 20, 2020
Jan 19, 2020
Jan 18, 2020
Jan 17, 2020
Jan 16, 2020
Jan 15, 2020
Jan 13, 2020
Jan 12, 2020
Jan 11, 2020
Jan 10, 2020
Jan 9, 2020
Jan 8, 2020
Jan 7, 2020
Jan 6, 2020
Jan 5, 2020
Jan 4, 2020
Jan 3, 2020
Jan 2, 2020
Jan 1, 2020
Dec 31, 2019
Dec 30, 2019
Dec 29, 2019
Dec 28, 2019
Dec 27, 2019
Dec 26, 2019
Dec 25, 2019
Dec 24, 2019
Dec 23, 2019
Dec 22, 2019
Dec 21, 2019
Dec 20, 2019
Dec 19, 2019
Dec 18, 2019
Dec 17, 2019
Dec 16, 2019
Dec 15, 2019
Dec 14, 2019
Dec 13, 2019
Dec 12, 2019
Dec 11, 2019
Dec 10, 2019
Dec 9, 2019
Dec 8, 2019
15
10
5
0
WHO declares “public
health emergency of
international concern”
Lunar New Year
national holiday
Nationwide mandatory
extended holiday
Another 15
cities shut
down
Wuhan City
shut down
COVID-19
a Class B
notifiable
disease
2019-nCoV
identified
Huanan Seafood
Market closed
2019-nCoV
sequences
first
shared
2019-nCoV test
kits first available
Wuhan Health Commission
alerts National Health
Commission and China CDC,
and WHO is notified
3 More cases of
pneumonia found in HICWM
Hospital (for a total of 7)
Dr Zhang reported unusual
pneumonia cases to the
local CDC
4 Unusual cases of pneumonia
(3 in the same family) noticed by
Jixian Zhang, MD, in HICWM Hospital
Active case finding
begins in Wuhan City
Daily numbers of confirmed cases are plotted by date of onset of symptoms (blue) and by date of diagnosis
(orange). Because, on retrospective investigation, so few cases experienced illness in December,these cases are
shown in the inset. The difference between the cases by date of symptom onset curve (blue) and the cases by
date of diagnosis curve (orange) illustrates lag time between the start of illness and diagnosis of COVID-19 by viral
nucleic acid testing. The graph's x-axis (dates from December 8, 2019, to February 11, 2020) is also used as a
timeline of major milestones in the epidemic response. The first few cases of pneumonia of unknown etiology are
shown in blue boxes on December 26 (n = 4) and 28-29 (n = 3). Most other cases that experienced onset of
symptoms in December were only discovered when retrospectively investigated. Major epidemic response
actions taken by the Chinese government are shown in brown boxes. The normally scheduled Lunar New Year
national holiday is shown in light yellow,whereas the extended holiday during which attendance at school and
work was prohibited (except for critical personnel such as health workers and police) is shown in dark yellow.
This figure was adapted with permission.
1
CDC indicates Chinese Center for Disease Control and Prevention;
HICWM, Hubei Integrated Chinese and Western Medicine; 2019-nCoV, 2019 novel coronavirus; WHO,World
Health Organization.
Opinion Viewpoint
E2 JAMA Publishedonline February 24, 2020 (Reprinted) jama.com
© 2020 American Medical Association. All rights reserved.
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(SARS; 2002-2003) and Middle East respiratory syndrome (MERS;
2012-ongoing) outbreaks. SARS was initiated by zoonotic transmis-
sion of a novel coronavirus (likely from bats via palm civets) in
markets in Guangdong Province, China. MERS was also traced
to zoonotic transmission of a novel coronavirus (likely from bats via
dromedary camels) in Saudi Arabia. All 3 viral infections commonly
present with fever and cough, which frequently lead to lower respi-
ratory tract disease with poor clinical outcomes associated with
older age and underlying health conditions. Confirmation of infec-
tion requires nucleic acid testing of respiratory tract samples
(eg, throat swabs), but clinical diagnosis may be made based on
symptoms, exposures, and chest imaging. Supportive care for
patients is typically the standard protocol because no specific
effective antiviral therapies have been identified.
The World Health Organization (WHO) declared the SARS out-
break contained on July 5, 2003. A total of 8096 SARS cases and
774 deaths across 29 countries were reported for an overall CFR of
9.6%. MERS is still not contained and is thus far responsible for
2494 confirmed cases and 858 deaths across 27 countries for a
CFR of 34.4%. Despite much higher CFRs for SARS and MERS,
COVID-19 has led to more total deaths due to the large number of
cases. As of the end of February 18, 2020, China has reported
72 528 confirmed cases (98.9% of the global total) and 1870
deaths (99.8% of the global total). This translates to a current
crude CFR of 2.6%. However, the total number of COVID-19 cases is
likely higher due to inherent difficulties in identifying and counting
mild and asymptomatic cases. Furthermore, the still-insufficient
testing capacity for COVID-19 in China means that many suspected
and clinically diagnosed cases are not yet counted in the
denominator.
2
This uncertainty in the CFR may be reflected by the
important difference between the CFR in Hubei (2.9%) compared
with outside Hubei (0.4%).
1,2
Nevertheless, all CFRs still need to be
interpreted with caution and more research is required.
Most secondary transmission of SARS and MERS occurred in
the hospital setting. Transmission of COVID-19 is occurring in this
context as well—3019 cases have been observed among health
workers as of February 11, 2020 (of whom there have been 1716
confirmed cases and 5 deaths).
1
However, this is not a major means
of COVID-19 spread. Rather, it appears that considerable transmis-
sion is occurring among close contacts. To date, 20 provinces
outside of Hubei have reported 1183 case clusters, 88% of which
contained 2 to 4 confirmed cases. Of note, 64% of clusters docu-
mented thus far have been within familial households (Chinese
Center for Disease Control and Prevention presentation made to
the WHO Assessment Teamon February 16, 2020). Thus, although
COVID-19seems to be more transmissible than SARS and MERS, and
many estimates of the COVID-19reproductive number (R
0
)haveal-
ready been published, it is still too soon to develop an accurate R
0
estimate or to assess the dynamics of transmission. More research
is needed in this area as well.
Response to the COVID-19 Epidemic
Since 2003, the Chinese government has improved its epidemic
response capacity. Some of these efforts are evident in the
response to COVID-19 (Figure 2). For example, in the 2002-2003
SARS outbreak, 300 cases and 5 deaths already had occurred by
the time China reported the outbreak to the WHO, whereas in the
COVID-19 outbreak, only 27 cases and zero deaths had occurred
when the WHO was notified (January 3, 2020) (Figure 2). From the
time of WHO notification, 2 months elapsed before SARS-CoV was
identified compared with only 1 week from the time of WHO notifi-
cation until 2019-nCoV was identified.
The timing of the COVID-19 outbreak, prior to China’s annual
Lunar New Year holiday, was an important factor as China consid-
ered how to respond to the outbreak. Culturally, this is the largest and
most important holiday of the year.It is the expectation that people
return to their family homes, which is the cause for the several bil-
lion person-trips made by residents and visitors during this time,
mostly on crowded planes, trains, and buses. Knowing this meant
each infected person could have numerous close contacts over a pro-
tracted time and across long distances, the government needed to
quickly act. However, it was not only the speed of the government’s
response, but also the magnitude of that response that were influ-
enced by the impending holiday travel time. Knowing that specific
treatment and prevention options, such as targeted antiviral drugs
and vaccines, were not yet available for COVID-19, China focused on
traditional public health outbreak response tactics—isolation, quar-
antine, social distancing, and community containment.
3-5
Identified case patients with COVID-19 were immediately iso-
lated in designated wards in existing hospitals, and 2 new hospitals
were rapidly built to isolate and care for the increasing numbers of
cases in Wuhan and Hubei. People who had been in contact with
COVID-19 cases were asked to quarantine themselves at home or
were taken to special quarantine facilities, where they could be
monitored for onset of symptoms. Enormous numbers of large
gatherings were canceled, including all Lunar New Year celebra-
tions, and traffic in Wuhan and in cities across Hubei was restricted
and closely monitored. Virtually all transportation was subse-
quently restricted at a national level. All of these measures were
instituted to achieve social distancing. In addition, an estimated
40 million to 60 million residents of Wuhan and 15 other surround-
ing cities within Hubei Province were subjected to community con-
tainment measures. Although these types of traditional outbreak
response actions have been successfully used in the past, they
have never been executed on such a large scale.
There have been some questions about whether these actions
are reasonable and proportional responses to the outbreak. Some
have argued that a number of these approaches may infringe on the
civil liberties of citizens, and some of these measures have been re-
ferred to as “draconian.” However, it is not only individual rights that
must be considered. The rights of those who are not infected, but
at risk of infection, must be considered as well. Whether these ap-
proaches have been effective (eg, in terms of reduced infections and
deaths averted), and whether these potential benefits have out-
weighed the costs (eg, economic losses), will be debated for years.
4,5
Next Steps
Importantly, another major goal of China’s current outbreak
response activities is to help “buy time” for science to catch up
before COVID-19 becomes too widespread. China must now focus
on adjusting tactics and strategies as new evidence becomes
available.
3,6
Much remains to be done and many questions
remain unanswered. China is very grateful for the help it is receiv-
ing from the international scientific, health, and public health
communities. The global society is more interconnected than ever,
and emerging pathogens do not respect geopolitical boundaries.
Viewpoint Opinion
jama.com (Reprinted) JAMA Published online February 24, 2020 E3
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Proactive investment in public health infrastructure and capacity
is crucial to effectively respond to epidemics like COVID-19, and
it is critical to continue to improve international surveillance, coop-
eration, coordination, and communication about this major out-
break and to be even better prepared to respond to future new
public health threats.
ARTICLE INFORMATION
Published Online: February 24, 2020.
doi:10.1001/jama.2020.2648
Conflict of Interest Disclosures: None reported.
Funding/Support: This work was supported by the
National Health Commission of the People’s
Republic of China (2018ZX10721102).
Role of the Funder/Sponsor:The funder had no
role in the preparation, review,or approval of the
manuscript, or the decision to submit the
manuscript for publication.
Disclaimer: The opinions expressed herein reflect
the collective views of the coauthors and do not
necessarily represent the official position of the
Chinese Center for Disease Control and Prevention.
Additional Contributions: We thank China CDC
Weekly for its permission to re-create the epidemic
curve with modifications.
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1. Novel Coronavirus Pneumonia Emergency
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the epidemiological characteristics of an outbreak
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(COVID-19)—China, 2020. China CDC Weekly.
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chinacdc.cn/en/article/id/e53946e2-c6c4-41e9-
9a9b-fea8db1a8f51
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ES.2020.25.6.2000110
Figure 2. Timeline Comparing the Severe Acute Respiratory Syndrome(SARS) and Coronavirus Disease 2019
(COVID-19)Outbreaks
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Dec 8: First case
Onset of symptoms in first known casea of pneumonia with
unknown etiology in Wuhan City, Hubei Province, China
Jan 7: New virus identified
Chinese scientists identify the pathogen
as a novel coronavirus
Jan 30: WHO global alert
WHO declares a “public health
emergency of international concern”
China
7736 confirmed cases
170 deaths
Feb 20: Current status
China
74 675 confirmed cases
2121 deaths
Dec 31: Reported to WHO
China reports a cluster of cases of pneumonia
with unknown etiology in Wuhan to WHO
China
27 cases
0 deaths
Outside China
82 confirmed cases
0 deaths
Outside China
1073 confirmed cases
8 deaths
Nov 16: First case
First known casea of atypical pneumonia
in Foshan City, Guangdong Province, China
Mar 12: WHO global alert
WHO issues a global alert on
“cases of severe respiratory illness
[that] may spread to hospital staff”
Jul 5: Final status
WHO declares worldwide containment
China
5327 cases
349 deaths
Feb 11: Reported to WHO
China reports an outbreak
of acute respiratory symptoms
in Guangdong to WHO
China
300 cases
5 deaths
Outside China
2769 cases
425 deaths
Apr 16: New virus identified
WHO scientists identify the pathogen
as a novel coronavirus
May 28: >8000 cumulative cases worldwide
Apr 28: >5000 cumulative cases worldwide
Apr 2: >2000 cumulative cases worldwide
SARS outbreak 2002-2003 COVID-19 outbreak 2019-2020
The timeline of events for the SARS
outbreak (left) from first case to final
worldwide containment. The timeline
of events for the COVID-19outbreak
(right) from the onset of symptoms
for the first case on December 8,
2019, to status on February20,
2020. Over the course of the first
2 months, more than 70 000 cases
have been confirmed and many more
are suspected. WHO indicates World
Health Organization.
a
Identified later retrospectively.
Opinion Viewpoint
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