Covid Working Group chief Dr NK Arora has said that according to research in India, a single shot had up to 61 per cent effectiveness against the Delta strain. A research conducted by Christian Medical College Vellore, which was based on a sample size of several thousands amid the surge in Delta variant, showed that a single dose of Covishield had a 61 per cent vaccine effectiveness which increased to 65 per cent with two doses, Dr NK Arora told.
As per Dr Arora, the survey was based on a sample size of several thousand and was conducted during the delta variant surge in the country. The chairperson of the COVID-19 Working Group added that the effectiveness increased to 65 percent after two doses. A British study published in the Lancet medical journal in early June looked at levels of neutralising antibodies produced in vaccinated people exposed to the Delta, Alpha (first identified in Britain) and Beta (first identified in South Africa) variants. Two doses of the Pfizer/BioNTech jab prevent 96 percent of hospitalisations due to the Delta variant, while AstraZenecais as effective at preventing hospitalisation in the case of 92 percent, according to a study involving 14,000 people. In the UK — where the Delta variant is now responsible for 96 percent of new cases — these findings pushed the government on Monday to reduce the waiting period between doses from 12 weeks to eight for people over 40.