Effectiveness of COVID-19 vaccine in prevention of mortality among moderate-severe cases: Case control study

Abstract

Introduction: The present study was conducted for vaccine effectiveness in the prevention of mortality among moderate to severe COVID-19 cases. Methods: The study was conducted in a dedicated COVID-19 hospital in Northern India from April 2021 to June 2021. Only moderate and severe COVID-19 cases were admitted to the hospital. All patients with the outcome (recovery or mortality) till 30 June 2021 constitute the study population for the study. The study is designed as a case-control study. The outcome was mortality due to COVID-19. The control group was cases who have recovered. The exposure was vaccination status. The data about the age, sex, and vaccination status including the type of vaccine was collected from the case sheets. Results: A total of 735 participants were recruited, out of which 409 patients survived and 326 patients died due to COVID-19 in the hospital. The mean age was 52.80 years (SD = 14.1 years) in the cases group and 60.92 years (SD = 14.97 years) in control group (P = 0.001). 137 (33.50%) were female and 272 (66.50%) were male in the control group while in cases 134 (41.10%) were female and 192 (58.90%) were male (P = 0.03). A total of 473 (64.35%) patients were unvaccinated, 199 (27.07%) were partially vaccinated, and 63 (8.57%) were fully vaccinated. Among the patients who survived, 101 (24.69%) were partially vaccinated and 28 (6.85%) were fully vaccinated; in the cases group, 98 (30.06%) people were partially vaccinated and 35 (10.74%) were fully vaccinated. On multiple regression analysis, there was no association between vaccination status and mortality among moderate and severe cases. Conclusion: The present study brought out that there is no association between vaccination and mortality among moderate to severe COVID-19 cases admitted to the makeshift hospital in Delhi.