NEW DELHI, June 22: A single dose of Covid-19 vaccine is effective in preventing deaths, according to a new analysis conducted by the Indian Council of Medical Research- National Institute of Epidemiology.
Vaccine effectiveness in preventing Covid-19 deaths with one and two doses was 82 per cent and 95 per cent respectively.
The study ‘Covid-19 vaccine effectiveness in preventing deaths among high-risk groups in Tamil Nadu” was published in the Indian Journal of Medical Research. The Tamil Nadu police department has been documenting vaccination of its workforce (as aggregate numbers with 0, 1 and 2 vaccine doses), and Covid-19 deaths during the second wave, along with details of the date of hospitalisation and vaccination.
The data was used to estimate the incidence of deaths due to Covid-19 among vaccinated and unvaccinated police personnel, Dr Manoj Murhekar, director of ICMR-NIE, said.
There are 117,524 police personnel working with the Department of Police in Tamil Nadu. Between February 1 and May 14 this year, 32,792 police personnel received one dose of Covid vaccine, 67,673 received two doses while 17,059 did not receive any vaccine dose.
Thirty-one Covid-19 deaths were reported among these police personnel between April 13, 2021 and May 14, 2021 . Of these 31 deceased, four had taken two doses of the vaccine, seven one dose and the remaining 20 were unvaccinated. The incidence of mortality among vaccinated and unvaccinated individuals was compared to calculate the relative risk of mortality associated with Covid-19 vaccination, researchers said.
Compared to unvaccinated individuals, the relative risk of Covid-19 deaths among those receiving one and two doses was 0.18 and 0.05 respectively.
Dr Murhekar said the results of their analyses are consistent with published studies showing effectiveness against severe disease. Published results of phase-3 clinical trial of Oxford AstraZeneca vaccine indicated efficacy of 97.5 per cent against hospitalisation. Observational studies conducted in different countries also indicated high effectiveness of the vaccine in preventing severe outcomes, Murhekar said.
The analysis did not study the effectiveness separately for each of the Covid 19 vaccines, he added. Another study is underway across 11 sites to estimate vaccine effectiveness against severe disease.
“It is necessary to increase coverage of Covid-19 vaccines, regardless of the type of vaccines, to reduce mortality in current as well as future waves of Covid-19 epidemic,” Dr Balram Bhargava, director general, ICMR, said.
(Manas Dasgupta)