COVISHIELD study shows breakthrough impact |
One of the largest studies anywhere in the world for COVISHIELD vaccine against COVID-19. The study includes 1.59 million healthcare and frontline workers of the Indian armed forces. Interim results of the study `Covishield AZD1222: Vaccine effectiveness among healthcare and frontline Workers of the Indian Armed Forces`, show a 93 percent reduction in breakthrough infections after vaccination with Covishield. The results of the study were published in a special issue of the peer-reviewed Medical Journal Armed Forces India on 27th July. The results underline the strong benefits of vaccination against breakthrough infections and deaths, and reiterate the message `Get Vaccinated, Stay Safe`. Air Commodore Subramanian Shankar, the corresponding author of the study, said that other studies had a sample size under 1 million. Shankar said their VIN-WIN cohort is possibly one of the largest studies worldwide on vaccine effectiveness. Healthcare workers and frontline workers of the armed forces were among the first to get their jabs after India started vaccinating on January 16 this year. The study presents an interim analysis of vaccine effectiveness estimates of 1.59 million recipients until May 30. The study says, `Data of 1,595,630 individuals (mean age 27.6 years; 99% male) over 135 days was analyzed. Till 30 May, 95.4% and 82.2% were partially and fully vaccinated. The study used anonymized data from the existing Armed Forces Health Surveillance system which had been enhanced for monitoring Covid-19. The system had data for daily vaccinations with first and second doses, dates of testing positive for Covid-19, and Covid-related deaths. As the shift occurred from unvaccinated to partially vaccinated and then fully vaccinated, the numbers in each group changed daily. Since each individual stayed in the three groups (UV, PV and FV) for varying lengths of time, the population at risk was measured in person-days. The crude rates were calculated by dividing infections/deaths by the population at risk and corrections were made for the force because of the pandemic`s second wave in April-May 2021, which was 600-1,000 times higher than in January. The study concluded that the mass roll-out of the first doses of the...vaccines was associated with substantial reductions in the risk of hospital admission due to Covid-19. The VIN-WIN study mentions results of other Covishield vaccine effectiveness studies as well. The study helps prove vaccine efficacy and scientific evidence is being used to help overcome vaccine hesitancy.
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