Single COVID vaccine shot also effective in preventing deaths: ICMR-NIE study

Even a single dosage of the COVID-19 vaccine, according to the Indian Council of Medical Research-National Institute of Epidemiology (ICMR-NIE), is effective in preventing deaths. The ICMR study stated, "Our analysis indicated that COVID-19 vaccination, even with a single dose, was effective in preventing deaths. It is necessary to increase coverage of COVID-19 vaccines, regardless of the type of the vaccines, to reduce the mortality in current, as well as in future waves of COVID-19 epidemic."

COVID-19 vaccine dose effective

The study was conducted on the Tamil Nadu Police. During the second wave, the department had been tracking vaccination of its employees (as aggregate numbers with 0, 1, and 2 doses) and COVID-19 deaths, as well as the dates of hospitalisation and immunisation. The data (personal communication) were used in the study to assess the incidence of COVID-19-related mortality among vaccinated and unvaccinated police officers.

The study said, "There are 1,17,524 police personnel working with the department of Police in Tamil Nadu. Between February 1, 2021, and May 14, 2021, 32,792 received a single dose, 67,673 received two-doses while the 17,059 did not receive any vaccine dose."

Between April 13, 2021, and May 14, 2021, 31 COVID-19 deaths were documented among these police officers, according to the ICMR analysis (median age: 52 yr, range: 34-58, 29 males). The study stated, "Of these 31 COVID-19 deaths, four had taken two doses of the vaccine, seven had taken one dose and the rest 20 were unvaccinated. The incidence of COVID-19 deaths among the vaccinated with zero, one, and two doses were 1.17, 0.21, and 0.06 per 1000 police personnel respectively."

ICMR conducts study on the effect of COVID vaccine

The relative risk of COVID-19 deaths among those who received one and two doses was 0.18 and 0.05, respectively, when compared to uninfected persons, it noted.  With one and two doses, the vaccination proved successful in avoiding COVID-19 mortality by 82% and 95%, respectively. The Oxford AstraZeneca vaccine was shown to have a 97.5% efficacy against hospitalization in a phase-3 clinical trial that was recently published.

It added, "Observational studies conducted in different countries also indicated high effectiveness of the vaccine in preventing severe outcomes. The interim results of the BBV152 trial indicate high efficacy against preventing symptomatic disease. A cohort study conducted among healthcare workers from a tertiary care hospital in Tamil Nadu indicated a strong protective effect of two doses of vaccines against hospitalization, the need for oxygen therapy, and the need for ICU care. The results of our analyses are consistent with the published studies showing effectiveness against severe disease."

However, because the vaccination information was obtained as aggregated numbers, relevant confounders such as age, comorbidities, and previous exposure to COVID-19 infection could not be controlled for in the analysis. Furthermore, the efficiency of each vaccine could not be determined independently.

(with inputs from ANI)

Picture Credit: PTI