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Year : 2022  |  Volume : 19  |  Issue : 1  |  Page : 7-11

Outcomes of SARS-Cov-2 infection after COVID-19 vaccination in 1730 hospital admitted cases – An observational study from a tertiary care indian hospital

Deputy Director Medical Services office and Department of Internal Medicine & Allied Branches, Indraprastha Apollo Hospitals, New Delhi, India

Date of Submission27-Oct-2021
Date of Acceptance05-Nov-2021
Date of Web Publication28-Jan-2022

Correspondence Address:
Amit Roy
Indraprastha Apollo Hospitals, Sarita Vihar, Delhi Mathura Road, New Delhi - 110 076
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/am.am_121_21

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Background and Aims: This study aimed to ascertain a number of SARS-CoV-2 infections in patients who had received either dose of vaccination, admitted in a tertiary care center, in New Delhi, and make a comparison with morbidity and mortality. Methods: Data were collected from COVID-19 patients admitted from April 1, 2021, to May 31, 2021. It included the type of vaccination (ChAdOx1 nCoV-19 or BBV152) and the number of doses taken. Mortality and morbidity data were collected and compared based on the computed tomography (CT) severity score. Results: Among 1730 patients, 477 (27.5%) were vaccinated, of which 389 received ChAdOx1 nCoV-19 and 63 received BBV152 vaccine. In 46 patients with breakthrough infection, 7 succumbed. Observed mortality rate was 11.4% (197), of which 53 received a single dose, 11 were completely vaccinated, and 144 were unvaccinated. Among patients who took only one dose, CT severity was mild in 24, moderate in 131, and severe in 27 cases. In fully vaccinated, it was mild in 7, moderate in 22, and severe in just 1 case. Among unvaccinated, 53 had a mild, 349 moderate, and 67 a severe score. Comorbidities were noted in 103 expired patients. Conclusions: The study shows that <30% of patients were vaccinated. Only a handful had completed both doses. Reassuringly, only one among the fully vaccinated had a severe CT score. Although comorbidity influences the prognosis, most of the completely vaccinated who succumbed had no comorbidity. Hence, more research and larger data need to be gathered regarding postvaccination COVID-19 infection.

Keywords: BBV152 vaccine, ChAdOx1 nCoV-19 recombinant coronavirus vaccine, comorbidities, computed tomography severity score, COVID-19, morbidity, mortality, SARS-COV-2, vaccination

How to cite this article:
Roy A, Dey G. Outcomes of SARS-Cov-2 infection after COVID-19 vaccination in 1730 hospital admitted cases – An observational study from a tertiary care indian hospital. Apollo Med 2022;19:7-11

How to cite this URL:
Roy A, Dey G. Outcomes of SARS-Cov-2 infection after COVID-19 vaccination in 1730 hospital admitted cases – An observational study from a tertiary care indian hospital. Apollo Med [serial online] 2022 [cited 2022 May 21];19:7-11. Available from: https://www.apollomedicine.org/text.asp?2022/19/1/7/336754

  Introduction Top

The ongoing infection of COVID-19 originated in Wuhan, China, and has spread to more than 210 countries around the globe including India.[1] As of July 1, 2021, 181,722,790 total cases have been recorded in India and 3,942,233 deaths have been confirmed.[2]

The main receptor of SARS-CoV-2 for entry is the ACE-2 protein, which is very abundant in alveolar tissue, making the lungs the primary target of the illness.[3] The disease usually presents with fever and respiratory symptoms such as cough and shortness of breath.[4],[5]

At the moment, there are many vaccine candidates simultaneously in the pipeline for COVID-19 than ever before for an infectious disease, all trying to achieve the same thing – immunity to the virus, and some might even be able to stop transmission. They are able to do so by stimulating an immune response to an antigen found on the virus. In case of COVID-19, the antigen is the characteristic spike protein found on the surface of the virus, which it uses to invade human cells. There are four categories of vaccines in clinical trials: whole virus, protein subunit, viral vector, and nucleic acid (RNA and DNA).[6]

The vaccination campaign for COVID-19 in India was started on January 16, 2021, using two vaccines: ChAdOx1 nCoV-19 recombinant coronavirus vaccine (manufactured by AstraZeneca) and BBV152 vaccine (by Bharat Biotech). The recipients of vaccines include all health-care workers, frontline workers, and people who are more than 45 years of age with morbidities (such as diabetes and coronary artery disease). From May 1 onwards, vaccination has been opened to all individuals (>18 years of age) in India.[7] As of June 30, 2021, total vaccinations given were 2,915,585,182.[2]

Vaccine breakthrough cases after vaccinations are a matter of concern, but adequate data regarding these infections are not available in the real-world setting. The CDC defines “a vaccine breakthrough infection is defined as the detection of SARS-CoV-2 RNA or antigen in a respiratory specimen collected from a person ≥14 days after they have completed all recommended doses of a U. S. Food and Drug Administration-authorized COVID-19 vaccine”.[8] Vaccines have effectiveness in decreasing the risk of getting COVID-19 infections by 70%–90%, and also protect from severe infection. It is, therefore, possible that some people who are fully vaccinated against COVID-19 may get infected by SARS-CoV-2. Anecdotal reports (unpublished) from India and published reports from other parts of the world indicate these infections are occurring but are rare. And also, it appears that these breakthrough cases are either asymptomatic or mild to moderate in nature, rarely causing severe disease.[7]

The spread of COVID-19 infection continues unrelentingly throughout India, although vaccinations are now open to all adults. We aimed to ascertain a number of SARS-CoV-2 infections in patients who had received either dose of vaccination, admitted in a tertiary care center in New Delhi, India, and make a comparison with morbidity and mortality.

Aims and objectives

  1. Number of patients who suffered from COVID-19 infection after first dose of vaccination
  2. Number of patients who suffered from COVID-19 infection after second dose of vaccination
  3. Morbidity and mortality among patients who have received COVID-19 vaccination.

  Methods Top

Data were collected from patients admitted in a tertiary care Indian hospital who were suffering from COVID-19 infection from April 1, 2021, to May 31, 2021, after obtaining their consent. Declaration of patient consent form was filled for all patients. Detailed data regarding vaccinations were collected which included type of vaccination (ChAdOx1 nCoV-19 recombinant coronavirus vaccine or BBV152 vaccine) and the number of doses taken. Mortality along with comorbidities (such as hypertension, diabetes, chronic kidney disease, and chronic liver disease) and morbidity data were also collected and compared. Morbidity data were collected in the form of the 25-point computed tomography (CT) severity score of the admitted patients (wherever available) and it was compared. Studies have shown that the CT severity score correlates with the clinical severity of the patients suffering from COVID-19 infection. Based on the total score, condition of the patients can be categorized as mild (7 or less), moderate (8–17), and severe (18 or more):[9]

A total of 1730 patients were found to be admitted between April 1, 2021, and May 31, 2021. Required data were collected as described above and were tabulated. Data was entered in Microsoft excel and analysis was done using SPSS version 22.0.The description of the data will be done in form of arithmetic mean +/- SD for quantitative data while in the form of frequencies (%) for qualitative (categorical) data P-values of < 0.05 will be considered significant. For comparison of categorical variables (i.e. to examine the associations between qualitative/quantitative variables), chi-square test will be use. Student t-test (independent, two tailed) will be been used to find out the significance of study parameters on a continuous scale between two groups. Logistic regression was used to find the odds ratio (P < 0.05). Since this is a retrospective, observational study of the data, not involving any patient intervention, the Institutional Ethical Committee approval was not obtained.

  Results Top

It was seen that a total of 1730 COVID-19 affected patients were admitted in the tertiary care center between April 1, 2021, and May 31, 2021, out of which 1118 (64.6%) were male and 612 (35.4%) were female. Maximum number of vaccinated people belonged to the age group of more than 60 years (234) and the mean age was found to be 55.7 with a standard deviation of 16.38 [Table 1].
Table 1: Demographic details of the study

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A total of 477 (27.5%) individuals were found to be vaccinated. It was noted that most people were vaccinated with ChAdOx1 nCoV-19 recombinant coronavirus vaccine. Data revealed that 389 patients had taken the ChAdOx1 nCoV-19 coronavirus vaccine by AstraZeneca, among them 345 had taken only first dose of vaccination and 44 had completed both doses. Only 63 individuals had taken BBV152 Vaccine by Bharat Biotech (54 had taken only the first dose, while only 9 had taken both doses). In addition, 25 people gave a history of being vaccinated but could not recall whether it was ChAdOx1 nCoV-19 coronavirus vaccine or BBV152 vaccine (only 5 had received one dose and 20 had gotten both doses).

In our study, 46 patients out of the 73 patients who had taken both the doses were found to fit the criteria of breakthrough infections as defined by CDC. Among them, 29 had taken ChAdOx1 nCoV-19 vaccine, 7 had received BBV152 vaccine and 10 individuals had received both the doses but did not know which vaccine they received. Unfortunately, it was found that seven patients who had suffered from breakthrough infection succumbed to the illness and among them, three had a history of one or more comorbidities.

A mortality rate of 11.4% (197) was observed among the admitted patients, out of which 53 patients had taken the first dose (47 had taken the ChAdOx1 nCoV-19 recombinant coronavirus vaccine, only 3 had taken the BBV152 vaccine, and 3 had taken the first dose but could not recall which vaccine) and 11 among them had taken both doses (8 had taken both doses of ChAdOx1 nCoV-19 recombinant coronavirus vaccine and 3 could not recall which vaccine was given to them). Therefore, it was seen that the risk of mortality due to COVID-19 was 0.71 times less among patients who got the second dose of vaccination (odds ratio [OR] = 0.74, 95% confidence interval [CI] = 0.37–1.38).

A multivariate analysis revealed that the mean age of expired was 63.17 ± 15.97 years. The risk of mortality due to COVID-19 was less in all the age groups except those who belonged to the group of >60 years. Furthermore, it was seen that 132 (67%) males had expired due to COVID-19, while only 65 (33%) females had expired, showing that the risk of mortality due to COVID-19 was 0.88 times less among females than males (OR = 1.13, 95% CI = 0.82–1.54).

It was observed that among the 197 patients who had expired, 103 had one or more comorbidities and among these individuals, 21 had taken the first dose of vaccination and 5 had taken both doses which was statistically significant (P = 0.001). Out of those five, three patients fall under the category of breakthrough infection.

CT severity score was compared and correlated with individuals who had taken first dose of the vaccine, both doses of the vaccine, and with those who had not been vaccinated [Table 2]. It was found that only 683 CT scores were available. Among people who had received the first dose of vaccination, it was seen that 24 had a mild score, 131 had a moderate score, and 27 had a severe score [Table 3]. Patients who had received both doses of the vaccine showed that only 7 had a mild CT score, 22 had a moderate score, and only one had a severe score. When scores were compared, statistical significance was found in comparison of mild and moderate CT score of people who had taken the first dose of vaccination with second dose of vaccination (P value 0.001). Patients who had not received any vaccination revealed that 53 had a mild score, 349 a moderate score, and 67 a severe score. Mortality was compared with the CT scores, and it was found that 2 (2.4%) patients died who had mild CT severity score, 30 (6%) patients died who had moderate CT severity score, and 18 (18.9%) patients died who had severe CT severity score, and it is found to be statistically significant (P value 0.001).
Table 2: Tabulated form of data of computed tomography severity score

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Table 3: Computed tomography severity score after the first dose of vaccination with P value

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  Discussion Top

Vaccine breakthrough infections after vaccinations are a matter of concern. Not much data are available regarding these infections. A recent statement from the All India Institute of Medical Sciences, Delhi, confirmed that none of the vaccinated people died due to COVID-19 disease. They conducted the first study on breakthrough infections during the April–May period; however, this has not been published in an academic journal yet.[10] Furthermore, the Indian Council of Medical Research states that 2–4 per 10,000 got infected with COVID-19 after vaccinations in India, but this as well is anecdotal.[11] Recent data from CDC stated that a total of 10,262 SARS-CoV-2 vaccine breakthrough infections had been reported from 46 U. S. states and territories as of April 30, 2021.[12]

Several studies related to breakthrough cases were carried out in various tertiary care facilities among health-care workers (HCWs) in India. A study conducted in a chronic care medical facility in New Delhi, India, involving 113 of its employees who had received COVID-19 vaccinations showed symptomatic breakthrough infections after the second dose in 15 persons (13.3%), and except one (required hospitalization), all 14 had mild COVID-19 disease.[7] Another study was conducted in a tertiary care hospital in Kerala, India, among its HCWs which showed that the breakthrough COVID-19 infections occurring after vaccination with two doses of ChAdOx1 nCoV-19 vaccine were mild in most of the HCWs. Even those HCWs who required hospitalization only had mild-to-moderate symptoms without any requirement for supplemental oxygen.[13] A similar study was also carried out in a medical college and hospital complex in New Delhi, India, among 326 HCWs with a mean age of 29.1 years. A total of 36 breakthrough infections were reported in the HCWs. Furthermore, COVID-19 infections occurred in 65 HCWs vaccinated with at least one dose of vaccine but prior to receiving their second dose or <14 days post second dose. Almost 94.4% of cases were mild and did not need supportive oxygen therapy.[14]

There is a possibility that breakthrough infections could be attributed to the various emerging COVID-19 variants. Hence, this area definitely requires a more detailed research.

In contrast, our study was conducted among admitted COVID-19 patients. Among the total admitted individuals, 477 vaccinated individuals developed COVID-19 infection among whom, 404 had taken only one dose and 73 had completed both doses. Reassuringly patients who had received both doses of the vaccine showed that only 5 had a mild CT score, 18 had a moderate score, and only one patient had a severe score.

Mortality of 11.4% was noted among all patients admitted. Among the 197 deceased patients, 103 of them had one or more comorbidities. The number of unvaccinated patients that succumbed to the disease was found to be 141, while 11 patients who had taken both doses of vaccine also died due to the disease. Among the expired patients who had one or more comorbidities, 21 individuals had taken the first dose of vaccination and only 5 had taken both doses.

A systematic review and meta-analysis done by Singh et al. to see association between comorbidities and mortality in COVID-19 indicates that the presence of comorbidities such as diabetes, hypertension, CVD, and COPD in individuals with COVID-19 is associated with an approximately twofold increased risk of developing severe symptoms and mortality.[15]

A similar meta-analysis was done involving seven studies by Biswas et al., including 1576 infected patients. When compared between severe and nonsevere patients, the pooled OR of hypertension, respiratory system disease, and cardiovascular disease were 2.36 (95% CI: 1.46–3.83), 2.46 (95% CI: 1.76–3.44), and 3.42 (95% CI: 1.88–6.22), respectively. It was found that underlying diseases, including hypertension, respiratory system disease, and cardiovascular disease, may be risk factors for severe patients compared with nonsevere patients.[16]

Limitations of this study are that this is a retrospective study and suffer from the disadvantages of such studies, compared to a prospective study. There was no control group of nonadmitted or nonvaccinated cohorts.

  Conclusions Top

The study shows that <30% of patients were vaccinated, where most of them had received the ChAdOx1 nCoV-19 recombinant coronavirus vaccine by AstraZeneca. Furthermore, among them, most individuals had received only the first dose of vaccination and only a handful had completed both doses. It was reassuring to find that among patients who had received both doses of the vaccination, only one developed a severe CT severity score. Although comorbidities are one of the major factors which influence the outcome of the illness, it was also noted that despite being completely vaccinated, patients with and without some form of comorbidity succumbed to the disease. The results of this study are reassuring that by taking both doses of vaccine, severe illness can be avoided mostly; however, more research and larger data need to be gathered regarding postvaccination COVID-19 infection.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Kaushik S, Kaushik S, Sharma Y, Kumar R, Yadav J. The Indian perspective of COVID-19 outbreak. Virus Disease. 2020;31:146-53.  Back to cited text no. 1
World Health Organization. COVID-19 Dashboard. Available from: https://covid19.who.int/region/searo/country/in. [Last accessed on 2021 Jul 09].  Back to cited text no. 2
Zhao Y, Zhao Z, Wang Y, Zhou Y, Ma Y, Zuo W. et al. “Single-Cell RNA Expression Profiling of ACE2, the Receptor of SARS-CoV-2.” American journal of respiratory and critical care medicine. 2020;202:756-9. doi:10.1164/rccm.202001-0179LE.  Back to cited text no. 3
Li LQ, Huang T, Wang YQ, Wang ZP, Liang Y, Huang TB, et al. COVID-19 patients' clinical characteristics, discharge rate, and fatality rate of meta-analysis. J Med Virol. 2020;92:577-83. doi: 10.1002/jmv.25757.  Back to cited text no. 4
Weiss P, Murdoch DR. Clinical course and mortality risk of severe COVID-19. Lancet 2020;395:1014-5.  Back to cited text no. 5
Tyagi K, Ghosh A, Nair D, Dutta K, Singh Bhandari P, Ahmed Ansari I, et al. Breakthrough COVID19 infections after vaccinations in healthcare and other workers in a chronic care medical facility in New Delhi, India. Diabetes Metab Syndr 2021;15:1007-8.  Back to cited text no. 7
Saeed GA, Gaba W, Shah A, Al Helali AA, Raidullah E, Al Ali AB, et al. Correlation between chest CT severity scores and the clinical parameters of adult patients with COVID-19 pneumonia. Radiol Res Pract 2021;2021:6697677.  Back to cited text no. 9
CDC COVID-19 Vaccine Breakthrough Case Investigations Team. COVID-19 vaccine breakthrough infections reported to CDC — United States, January 1–April 30, 2021. MMWR Morb Mortal Wkly Rep 2021;70:792-3.  Back to cited text no. 12
Niyas VKM, Arjun R. Correspondence: Breakthrough COVID-19 Infections among Health Care Workers after Two Doses of ChAdOx1 nCoV-19 Vaccine. QJM. 2021 Jun 12:hcab167.  Back to cited text no. 13
Medrxiv.org; 2021. Available from: https://www.medrxiv.org/content/10.1101/2021.06.07.21258447v1.full.pdf. [Last accessed on 2021 Jul 23].  Back to cited text no. 14
Singh A, Gillies C, Singh R, Singh A, Chudasama Y, Coles B, et al. Prevalence of co-morbidities and their association with mortality in patients with COVID -19: A systematic review and meta-analysis. Diabetes Obes Metab 2020;22:1915-24.  Back to cited text no. 15
Biswas M, Rahaman S, Biswas TK, Haque Z, Ibrahim B. Association of Sex, Age, and Comorbidities with Mortality in COVID-19 Patients: A Systematic Review and Meta-Analysis. Intervirology. 2020:1-12.  Back to cited text no. 16


  [Table 1], [Table 2], [Table 3]


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