Covishield vaccine reduced new Covid-19 cases by 93%, deaths by 98%: Centre
Covishield, the vaccine against Covid-19 manufactured by the Serum Institute of India, reduced fresh cases of the disease by 93% and reduced related deaths by 98%, the ministry of defence said on Tuesday citing a vaccine effectiveness study conducted by the Armed Forces Medical Services (AFMS).
At a press briefing earlier in the day, Niti Aayog member (health) Dr VK Paul said that the study was conducted on 1.5 million doctors and frontline workers. “Protection to the extent of 93% was seen (in people who were administered the Covishield vaccine) and this was during the second wave which was driven by the Delta variant of Covid-19... also 98%mortality reduction was seen,” Dr Paul said, while presenting the findings of the study.
The AFMS on Tuesday published the Vaccine effectiveness among healthcare and frontline workers of Indian Armed Forces (Vin-WIN) cohort study in Medical Journal Armed Forces India, a peer reviewed scientific journal.
According to the study, the Covishield vaccine reduced fresh infections by 93% and deaths by 98%. The study was largely conducted on healthy males with few comorbid illnesses. Moreover, children and the elderly were not included in the study. The study is possibly the largest study worldwide on Covid-19 vaccine effectiveness so far.
According to the press release, 1.59 million healthcare workers and frontline workers of the armed forces were among the first recipients when India launched the Covid-19 vaccination drive earlier on January 16.
Calculating vaccine effectiveness
Both the incident rate and the incident rate ratios were calculated by the authors in the Vin-WIN study. Vaccine effectiveness was calculated as a one-incident ratio.
Both crude and corrected rates were estimated and adjusted for the force of pandemic, second wave and the changing numbers in the three groups on a daily basis. The study was achieved at no additional cost by analysing available data, according to the official release.
The director general of the AFMS said that the study was carried out on anonymised data from the existing Armed Forces health surveillance system which had been enhanced for monitoring Covid-19, the release further showed.
Also, data about the daily vaccinations with first and second doses, dates of testing positive for Covid-19 and deaths were present in the surveillance system, which were analysed.