Impact of prior vaccination with CovishieldTM and Covaxin® on mortality among symptomatic COVID-19 patients during the second wave of the pandemic in South India during April and May 2021: a cohort study

Abstract

Background COVID-19 vaccines were authorised for emergency use to mitigate the impact of the pandemic. This study evaluated the effect of prior vaccination with either Oxford Astra Zeneca’s Covishield TM or Bharath Biotech’s Covaxin® on mortality among symptomatic COVID-19 patients during the second wave of the pandemic in India. Methodology In this cohort study comprising of RT-PCR confirmed symptomatic COVID-19 patients presenting during April and May 2021, the effect of prior vaccination on mortality (primary outcome), need for hospitalization, oxygen therapy, non-invasive ventilation (NIV) and intensive care unit (ICU) admission were assessed and expressed as risk ratio (RR) with 95% confidence intervals (CI). Results The mean (SD) age of the cohort (n=4183) was 46.3 (15.5) years; 17.9% (748/4183) had received at least one dose of Covishield TM and 4.8% (201/4183) had received Covaxin®. Mortality was 0.2% (95% CI: -0.2% - 0.7%), 3.5% (1.9% - 5.2%), 6.2% (0.3% - 12%) and 12.9% (11.8% - 14.1%) among fully vaccinated (>2 weeks after two doses), partially vaccinated (>2 weeks after one dose or <2 weeks after two doses), indeterminate (<2 weeks after one dose) and unvaccinated patients respectively. The difference in mortality among unvaccinated vs. fully vaccinated was 12.7% (95% CI: 11.4% - 13.9%), unvaccinated vs. partially vaccinated was 9.4% (7.4% - 11.4%) and unvaccinated vs. indeterminate vaccinated was 6.8% (0.8% - 12.7%). On adjusted analysis, as compared to unvaccinated patients, at least one dose of vaccine reduced the need for hospitalization (RR: 0.40; 95% CI: 0.35 - 0.47), oxygen (0.33; 0.27 - 0.40), NIV (0.23; 0.17 - 0.32), ICU admission (0.18; 0.12 - 0.27) and mortality (0.18; 0.11 - 0.29). Conclusion Among symptomatic COVID-19 patients, prior vaccination with Covishield TM or Covaxin® impacted the severity of illness and reduced mortality during a period of widespread delta variant circulation. Full vaccination conferred greater protection than partial vaccination.

Durability of ChAdOx1 nCoV-19 (Covishield®) Vaccine Induced Antibody Response in Health Care Workers

“…The studies from India showed that complete vaccination with Covishield ® yield an efficacy of up to 88.6% [ 26 ]. Other studies from India have also shown that ChAdOx1-nCoV-19 vaccine led to reduced severity of illness [ 27 ] as well as risk of mortality during the second wave of the pandemic [ 28 ].…”

The COVID-19 Vaccination Behavior and Correlates in Diabetic Patients: A Health Belief Model Theory-Based Cross-Sectional Study in China, 2021

“…Through COVID-19 vaccination and other comprehensive measures, the spread of COVID-19 [ 12 ] and the occurrence of severe disease after SARS-CoV-2 infection can be effectively decreased [ 13 ]. Vaccination usually has certain benefits in reducing the risk of severe SARS-CoV-2 infection and fatality according to published literature [ 14 ], but there were still concerns about the potential harmfulness of COVID-19 vaccination in some patients with diabetes in China (56.4%) [ 15 ], Saudi Arabia (29.0%) [ 16 ], Malaysia (24.7%) [ 17 ] and Italy (14.2%) [ 18 ]. The main factors correlated to the willingness to vaccinate against COVID-19 include fear of the adverse reactions to COVID-19 vaccination [ 17 ], uncertainty about the genetic composition of COVID-19 vaccines [ 16 ], and concern about the safety of COVID-19 vaccines [ 18 ].…”

The Relationship of COVID-19 Vaccination with Mortality Among 86,732 Hospitalized Patients: Subpopulations, Patient Factors, and Changes over Time

“…Little research has examined vaccination effects in hospitalized populations, patients that typically have the most severe COVID disease. While some studies track individuals as they transition from nonhospitalized to hospitalization status, 2,3,[6][7][8][9] there is less research on vaccination effects in large, hospitalized samples. Research with relatively small samples of hospitalized patients shows that vaccination reduces mortality.…”