Non-COVID Admissions to the ICU After COVID Vaccination: A Multicenter Study

Abstract

Introduction: The vaccination drive for COVID-19 was launched in India after the authorization of ChAdOx1
nCov-19 (Covishield), an adenoviral vector vaccine, and BBV152 COVID-19 (Covaxin), an inactivated virus
vaccine. As stated by the CDC, vaccine-related adverse events can happen. In this study, we aimed to assess
the timing of the COVID vaccination and admission diagnosis and their effect on ICU mortality. The time
from vaccination can help identify adverse events directly related to vaccination.
Methods: A retrospective cohort study was conducted across four centers in India. Patients who took the
first or second dose of any vaccines and were admitted with non-COVID illness to the ICU were included in
the study. Patients were categorized based on the time interval from vaccination as ≤42 days or >42 days. The
primary outcome was ICU mortality. The secondary outcomes were the length of ICU stay and duration of
mechanical ventilation.
Results: A total of 175 patients were included in the study. The mean age was 53.49 (15.89) years, and
61.14% were males. The ICU mortality was 24.57% (18.38% to 31.63%). Thromboembolic events such as
acute coronary syndrome (ACS), cerebrovascular accident (CVA), and mesenteric ischemia were seen in
7.43%, 7.43%, and 1.14% of patients, respectively. Six patients (3.43%) developed neuromuscular illness. The
mortality was higher in patients >66 years, followed by ≤35 years of age when admitted ≤42 days of
vaccination (p=0.008). The mortality was higher in cerebrovascular disorders and was clinically significant
(p<0.001).
Conclusion: Patients developed thromboembolic events and neuromuscular diseases requiring ICU
admission post-COVID vaccination. We observed a significantly higher mortality in the age groups >66 years
and ≤35 years when admitted within 42 days of COVID vaccination. Patients admitted with cerebrovascular
diseases also had higher mortality.

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Review began 09/21/2024
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Published 10/15/2024
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DOI: 10.7759/cureus.71534
Non-COVID Admissions to the ICU After COVID
Vaccination: A Multicenter Study
Amarja A. Havaldar , Kaladhar Sheshala , Raman Kumar , Abhilash Chennabasappa , Ria R. Thomas ,
Sumithra Selvam
1. Critical Care Medicine, St. John's Medical College Hospital, Bengaluru, IND 2. Critical Care Medicine, Yashoda
Hospital, Hyderabad, IND 3. Anesthesiology, Rajendra Institute of Medical Sciences, Ranchi, IND 4. Critical Care
Medicine, Jagadguru Sri Shivarathreeshwara Medical College and Hospital, Mysuru, IND 5. Biostatistics, St John's
Research Institute, Bengaluru, IND
Corresponding author: Amarja A. Havaldar, amarjahavaldar2009@gmail.com
Abstract
Introduction: The vaccination drive for COVID-19 was launched in India after the authorization of ChAdOx1
nCov-19 (Covishield), an adenoviral vector vaccine, and BBV152 COVID-19 (Covaxin), an inactivated virus
vaccine. As stated by the CDC, vaccine-related adverse events can happen. In this study, we aimed to assess
the timing of the COVID vaccination and admission diagnosis and their effect on ICU mortality. The time
from vaccination can help identify adverse events directly related to vaccination.
Methods: A retrospective cohort study was conducted across four centers in India. Patients who took the
first or second dose of any vaccines and were admitted with non-COVID illness to the ICU were included in
the study. Patients were categorized based on the time interval from vaccination as ≤42 days or >42 days. The
primary outcome was ICU mortality. The secondary outcomes were the length of ICU stay and duration of
mechanical ventilation.
Results: A total of 175 patients were included in the study. The mean age was 53.49 (15.89) years, and
61.14% were males. The ICU mortality was 24.57% (18.38% to 31.63%). Thromboembolic events such as
acute coronary syndrome (ACS), cerebrovascular accident (CVA), and mesenteric ischemia were seen in
7.43%, 7.43%, and 1.14% of patients, respectively. Six patients (3.43%) developed neuromuscular illness. The
mortality was higher in patients >66 years, followed by ≤35 years of age when admitted ≤42 days of
vaccination (p=0.008). The mortality was higher in cerebrovascular disorders and was clinically significant
(p<0.001).
Conclusion: Patients developed thromboembolic events and neuromuscular diseases requiring ICU
admission post-COVID vaccination. We observed a significantly higher mortality in the age groups >66 years
and ≤35 years when admitted within 42 days of COVID vaccination. Patients admitted with cerebrovascular
diseases also had higher mortality.
Categories: Emergency Medicine, Internal Medicine, Anesthesiology
Keywords: bbv152, chadox1 ncov-19, covaxin, covid-19, covishield, guillian barre syndrome, vaccination, vitt
Introduction
Various strategies were used to contain the pandemic and to treat COVID-19 patients. With the emergency
authorization of vaccines after initial phase III trials, the vaccination program was rolled out on 16th
January 2021, in India [1]. Initially, vulnerable groups and frontline workers were given the vaccination, and
over the next few months, it was made available to the general public.
There were concerns about the effectiveness and adverse events related to vaccination. The initial study by
Kewan et al. reported adverse events after COVID vaccination requiring emergency department visits within
10 days [2]. The case series, including five patients, described the development of vaccine-induced
thrombocytopenia (VITT) after ChAdOx1 nCov-19 (Covishield) [3]. As per the CDC report, the complications
can occur within six weeks, i.e., 42 days, following vaccination [4]. There is limited information from India
about adverse events after vaccination, and it is only restricted to case reports, system-specific events, or
limited to self-reporting of adverse events by the people [5-6]. Information about admissions after COVID
vaccination is still important to identify any short-term or long-term effects directly related to vaccination
for safety and quality purposes. We aimed to see the association between the time interval between COVID
vaccination and admission diagnosis and their effect on ICU mortality.
Materials And Methods
Design and settings
1 2 3 4 1
5
Open Access Original Article
How to cite this article
Havaldar A A, Sheshala K, Kumar R, et al. (October 15, 2024) Non-COVID Admissions to the ICU After COVID Vaccination: A Multicenter Study.
Cureus 16(10): e71534. DOI 10.7759/cureus.71534

This study was conducted from 1st April 2021 to 31st December 2021. As this was a retrospective cohort
study, a waiver for informed consent was obtained from the Institutional Ethics Committee (IEC) (approval
no. 149/2021) of St. John’s Medical College Hospital. The study was registered with the Clinical Trial
Registry India (CTRI; 2021/07/034587) on 05/07/2021. The IEC approvals from the respective participating
centers were obtained. A total of four centers were included from India.
The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines were
followed. After IEC approval from each center, the data collection process was initiated. This study is a part
of the Postcovac study [7].
Participants
The patients who received the first or second dose of any of the COVID vaccines were included in the study.
The baseline characteristics of the patients were collected. Information about the type of vaccine and the
number of doses received was collected. Time from vaccination was calculated as the difference between the
timing of the vaccination, i.e., either the first or second dose, whichever was the latest, and the ICU
admission for non-COVID illness. The time from vaccination was divided into two categories: ≤42 days and
>42 days. Acute physiology and chronic health evaluation (APACHE II) and sequential organ failure
assessment (SOFA) scores were calculated. The admission diagnosis was classified into 10 subgroups. The
primary outcome was ICU mortality. The secondary outcomes were the length of ICU stay and duration of
mechanical ventilation.
Data analysis
Statistical analysis was done using STATA version 15 (StataCorp LLC, College Station, TX, USA). Continuous
variables were presented as mean (standard deviation (SD)) and median (interquartile range (IQR)) as
applicable. Categorical variables were presented as percentages. Continuous variables were analyzed by an
independent t-test or Mann-Whitney U test as applicable. The chi-square test was used to test the
association between categorical variables. Logistic regression was done to test the association between ICU
mortality and time from vaccination adjusted for age, gender, presence of comorbidities, and APACHE II
score in different models. The p-value of <0.05 was considered statistically significant.
Results
Among the 506 patients who were screened, 175 vaccinated patients were enrolled in the study based on the
inclusion criteria from four centers. The clinical characteristics of the study population are presented in
Table 1. The mean age was 53.49 ± 15.89 years, and 61.14% were males. The median APACHE II and SOFA
scores were 17 (11 to 24) and 7 (5 to 9), respectively (Table 1). Information about the type of vaccine received
was collected. The median time from vaccination to ICU admission was 55 (25 to 85) days, and 41.7% were
admitted within ≤42 days of vaccination.
2024 Havaldar et al. Cureus 16(10): e71534. DOI 10.7759/cureus.71534 2 of 8

Parameters Values (total n=175)
Age¥53.49 ± 15.89
≤35 27 (15.43)
36 to 50 43 (24.57)
51 to 60 60 (34.29)
≥66 45 (25.71)
Gender
Male/female 107/68 (61.14/38.86)
Time from vaccination to hospital admission 55 (25, 85)
≤42 days 73 (41.7%)
>42 days 102 (58.3%)
Vaccination
Single dose /Two doses 92/83 (52.57/47.43)
Type of vaccine
Covishield vs. Covaxin 142/27 (84.02/15.98)
Comorbidities
Diabetes mellitus 70 (40)
Hypertension 78 (44.57)
CKD 16 (9.14)
CVA 15 (8.57)
IHD 25 (14.29)
COPD 8 (4.57)
Bronchial asthma 3 (1.71)
TB 4 (2.29)
Immunosuppressants 8 (4.57)
Malignancy 3 (1.71)
Scores
APACHE II score 17 (11-24)
SOFA score 7 (5-9)
TABLE 1: Clinical characteristics of the study population
Values are presented as n (%), ¥ mean (SD), and median (25th and 75th perc entiles).
CKD: Chronic kidney disease, CVA: Cerebrovascular accident, IHD: Ischemic heart disease, COPD: Chronic obstructive pulmonary disease, TB:
Tuberculosis, APACHE: Acute physiology and chronic health evaluation, SOFA: Sequential organ failure assessment
The overall time taken for admission diagnosis of the patients in the ICU and the time from vaccination for
≤42 days and >42 days are presented in Table 2. The most common admission diagnosis was sepsis (38.86%).
Acute coronary syndrome (ACS) (7.43%), cerebrovascular accident (CVA) (7.43%), and mesenteric ischemia
(1.14%) were the possible thromboembolic events (16%). Two patients had mesenteric ischemia after 64 and
100 days after vaccination, respectively. Six patients (3.43%) had neuromuscular illness (Guillian Barre
syndrome (GBS), myasthenia gravis, or any other), of which three patients presented with GBS. Among these
three patients, GBS was diagnosed within six weeks in two patients and within two days after the second
2024 Havaldar et al. Cureus 16(10): e71534. DOI 10.7759/cureus.71534 3 of 8

dose in one patient. One patient developed demyelinating polyradiculopathy with brainstem involvement
(atypical GBS) 15 days after the vaccination. Two patients developed myasthenia gravis six weeks after
vaccination. Intracranial bleeding was seen in 6.86% of the patients. There was no significant difference in
the admission diagnosis, length of ICU stay, or duration of mechanical ventilation between the time from
vaccination in ≤42 and >42 days. Also, admission diagnosis was comparable to the type of vaccine received.
Admission diagnosis All (total
n=175)
Time from vaccination ≤42 days
(total n=73)
Time from vaccination >42 days (total
n=102)
p-
value
Mortality 24.57% 30.14% 20.59 % 0.148
ACS 13 (7.43) 4 (5.48) 9 (8.82)
0.165
CVA 13 (7.43) 6 (8.22) 7 (6.86)
Mesenteric ischemia 2 (1.14) 0 (0) 2 (1.96)
Neuromuscular diseases 6 (3.43) 2 (2.74) 4 (3.92)
Intracranial bleeding 12 (6.86) 5 (6.85) 7 (6.86)
Sepsis 68 (38.86) 23 (31.51) 45 (44.12)
Tropical fever 17 (9.71) 12 (16.44) 5 (4.90)
Other diagnosis 30 (17.14) 12 (16.44) 18 (17.65)
Hepatic 9 (5.14) 6 (8.22) 3 (2.94)
Renal 5 (2.8) 3 (4.11) 2 (1.96)
Length of ICU stay 7 (3-13) 6 (3-10) 7 (4-15) 0.072
Duration of mechanical
ventilation 4 (3-8) 4 (3-5) 4 (3-8) 0.762
TABLE 2: Admission diagnosis and timing from vaccination
Values are presented as n (%) and p-value from the chi-square test of association.
ACS: Acute coronary syndrome, CVA: Cerebrovascular accident
The overall mortality was 24.57% (18.38% to 31.63%). The association of clinical characteristics between
survivors and non-survivors is presented in Table 3. Time from vaccination to ICU admission was
significantly lower in non-survivors compared to survivors (p=0.033). Although statistically not significant,
the proportion of mortality (30.14%) was higher in patients admitted within 42 days post-vaccination as
compared to those admitted after 42 days of vaccination (20.59%), p=0.148. The APACHE and SOFA scores
were significantly higher in non-survivors (p<0.001) (Table 3). Adjusted for age, gender, diagnosis, and the
presence of comorbidities (diabetes mellitus and hypertension), an increased number of days after
vaccination had a lower risk of mortality (adjusted odds ratio (AOR): 0.989, 95% CI, 0.980-0.998, p=0.020).
After adjusting for APACHE II along with the above-mentioned variables in the model, the time from
vaccination remained significantly associated with mortality (AOR: 0.990, 95% CI, 0.980-0.999, p=0.042).
2024 Havaldar et al. Cureus 16(10): e71534. DOI 10.7759/cureus.71534 4 of 8

Parameters Survivors (total n=132) Non-survivors (total n=43) p-value
Age¥52.44 (15.29) 56.72 (17.42) 0.126
Gender: Male/female 80/52 (60.61/39.39) 27/16 (62.79/37.21) 0.799
Time from vaccination to hospital admission (days) 58.5 (28, 87) 37 (15, 79.0) 0.033
Time from vaccination ≤42 days 51 (69.86) 22 (30.14)
0.148
Time from vaccination >42 days 81 (79.41) 21 (20.59)
Any vaccination: Single dose/two Doses 64/68 (48.48/51.52) 28/15 (65.12/34.88) 0.058
Type of vaccine: Covishield vs. Covaxin 108/20 (84.38/15.63) 34/7 (82.93/17.07) 0.826
Comorbidities
Diabetes mellitus 52 (39.39) 18 (41.86) 0.774
Hypertension 55 (41.67) 23 (53.49) 0.176
CKD 11 (8.33) 5 (11.63) 0.515
CVA 13 (9.85) 2 (4.65) 0.290
IHD 16 (12.12) 9 (20.93) 0.152
COPD 7 (5.30) 1 (2.33) 0.417
Bronchial asthma 3 (2.27) 0 (0) 0.319
TB 3 (2.27) 1 (2.33) 0.984
Immunosuppressants 4 (3.03) 4 (9.30) 0.087
Malignancy 3 (2.27) 0 (0) 0.319
Scores
APACHE II score* 14 (9-22) 19.5 (17-24) <0.001
SOFA score* 6 (4-8.5) 9 (7-11) <0.001
TABLE 3: Association of clinical characteristics between survivors and non-survivors
¥Mean (SD): The independent sample t-test was used for comparison; *Median (IQR): Mann-Whitney U test was used for com parison. Values are
presented as n (%).
CKD: Chronic kidney disease, CVA: Cerebrovascular accident, IHD: Ischemic heart disease, COPD: Chronic obstructive pulmonary disease, TB:
Tuberculosis
In the subgroup analysis of patients admitted within 42 days post-vaccination, the proportion of mortality
was significantly higher in the ≤35 years and >66 years age groups compared to the middle-aged group of
patients (p=0.008). After 42 days of vaccination, there was no significant association noted between age
categories and mortality (Figure 1).
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FIGURE 1: Age-wise distribution of mortality
Among non-survivors in the ≤35years of age group and admitted within 42 days of vaccination, the
admission diagnoses were intracranial bleeding, liver failure, fever with demyelinating polyradiculopathy
(atypical GBS) with brainstem involvement, and tropical fever with thrombocytopenia (platelet factor 4
(PF4) antibodies were negative and the patient had brainstem dysfunction). One patient diagnosed with pre-
eclampsia developed puerperal sepsis.
Discussion
In our study, 175 patients were admitted post-vaccination with non-COVID illness during the study period.
The admission diagnosis possibly related to vaccination includes thromboembolic events and neuromuscular
illness. Higher mortality was observed in the age group >66 years and ≤35 years when the time from
vaccination was ≤42 days. The ICU mortality was 24.57%.
The common complications reported in different studies are vaccine-induced immune thrombotic
thrombocytopenia (VITT), thromboembolic complications, and neurological complications. Vaccine-induced
immune thrombotic thrombocytopenia was reported within one week of receiving the vector-based
Covishield vaccine, and PF4 antibodies were positive [8-12]. A single-center study evaluated coronary
thrombosis post-vaccination within three months, but the causality could not be determined [6]. Systematic
review and case series evaluating thromboembolic complications post-vaccination showed the median
duration for the development of these complications was 10.8+7.8 days and PF4 antibodies were present in
78.6% of patients [4,13,14].
There are different neurological complications described after vaccination [15]. Guillian Barre syndrome is a
known complication seen after various vaccinations, such as H1N1 [16]. This complication can occur up to
six to eight weeks post-vaccination. Similar case reports are seen post-COVID vaccination [17,18]. We
observed neuromuscular illness in six patients (3.16%).
The median time from vaccination to hospitalization was 55 (22 to 85) days, and for ACS, CVA,
neuromuscular illness, intracranial bleeding, and mesenteric ischemia, it was 75 (38 to 99), 44 (28 to 56), 50
(36 to 54), 94.5 (17 to 138.50), and 82 (64 to 100) days, respectively. Based on the published literature, the
reported thromboembolic events are observed within seven to 10 days, and neuromuscular illness in six to
eight weeks [4,16]. In our study, neuromuscular illness is possibly related to vaccination; however, causality
could not be determined. Time from vaccination alone was the significant factor in logistic regression after
adjusting for covariates, including APACHE II.
In our study, age-wise mortality observed in ≤35-year-old patients was 45.45% when the time from
vaccination was ≤42 days. The reasons for the higher mortality need to be studied in the larger population.
There are reports describing a higher incidence of myocarditis and mortality in a younger age group after
mRNA vaccination [19].
We classified admission diagnosis based on the International Classification of Diseases (ICD) 10 and
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compared the mortality with available literature [20]. The most common ICD10 code was I60-69, which
includes cerebrovascular diseases. As compared to other illnesses, the mortality in this group was higher as
compared to the published data (31.82% vs. 11.41%, p=0.001). This needs further evaluation in a larger
cohort.
There are various strengths to our study. It is one of the studies on the effect of timing from COVID
vaccination and admission diagnosis in patients admitted to the ICU with non-COVID illness. The available
published information regarding the adverse events is limited [17,21]. Our study gives an overview of
admission diagnosis in vaccinated patients, focusing more on thromboembolic and neuromuscular diseases.
There were certain limitations to our study. This is a retrospective study. We included patients vaccinated
with Covishield and Covaxin; hence, the side effects or adverse events observed in this study will not apply
to patients who received different types of vaccines. Patients who didn’t report to the hospital due to minor
side effects or had fatal outcomes were not included in this study. Hence, this may not give information
about the actual incidence of adverse events. The comparison between the unvaccinated cohort admitted
during the same time period would have helped in comparing the incidence of adverse events. We compared
a cohort of patients admitted before COVID to overcome this limitation [20]. As this vaccine is new, follow-
up of the vaccinated cohort is necessary to know the long-term effects of the vaccination, if any.
Conclusions
This study shows that adverse events, although rare, can occur after vaccination. We observed higher
mortality in extremes of age group when admitted within 42 days of vaccination. We also observed higher
mortality in patients with cerebrovascular diseases. A large population-based study is required to confirm
these findings.
Additional Information
Author Contributions
All authors have reviewed the final version to be published and agreed to be accountable for all aspects of the
work.
Concept and design: Amarja A. Havaldar, Sumithra Selvam
Acquisition, analysis, or interpretation of data: Amarja A. Havaldar, Kaladhar Sheshala, Raman Kumar,
Abhilash Chennabasappa, Ria R. Thomas, Sumithra Selvam
Drafting of the manuscript: Amarja A. Havaldar, Kaladhar Sheshala, Raman Kumar, Abhilash
Chennabasappa, Ria R. Thomas
Critical review of the manuscript for important intellectual content: Amarja A. Havaldar, Kaladhar
Sheshala, Raman Kumar, Abhilash Chennabasappa, Ria R. Thomas, Sumithra Selvam
Disclosures
Human subjects: Consent was obtained or waived by all participants in this study. Institutional Ethics
Committee, St. John's Medical College Hospital issued approval 149/2021. Animal subjects: All authors
have confirmed that this study did not involve animal subjects or tissue. Conf licts of interest: In
compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services
info: All authors have declared that no financial support was received from any organization for the
submitted work. Financial relationships: All authors have declared that they have no financial
relationships at present or within the previous three years with any organizations that might have an
interest in the submitted work. Other relationships: All authors have declared that there are no other
relationships or activities that could appear to have influenced the submitted work.
Acknowledgements
We would like to thank the staff of each participating hospital who helped in completing this project.
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