Covishield: Second vaccine dose in 3 months? Here's what AstraZeneca trial chief says
The coronavirus disease (Covid-19) vaccination programme in India has triggered much debate on the desired gap between the two doses of the vaccine. AstraZeneca, the pharmaceutical company behind the AZD1222 Covid-19 vaccine, being sold under the brand name 'Covishield' in India, has now backed the idea of keeping a 12-16 week gap between the two doses of its vaccine. The chief investigator of the AstraZeneca vaccine trials, in an interview with a news organisation on Friday, said that the level of protection provided by the vaccine significantly increases in the second and third months after taking the shot.
India recently decided to extend the gap between the two doses of Covishield to 12 to 16 weeks from six to eight weeks. There has been a lot of contention over this decision, particularly because of varied opinions of vaccine efficacy and different countries pursuing markedly different approaches regarding the duration between two vaccine doses.
Professor Andrew Pollard, who supervises the team conducting the Oxford-AstraZeneca vaccine trials, said that the Covid-19 vaccination policies in the United Kingdom and India should not be compared with one another due to the vastly different circumstances in the two countries. The goal of the immunisation policy in India, he said, is to ensure at least one dose of the Covid-19 vaccine for the largest number of people at the earliest, which is understandable with regards to the present coronavirus disease (Covid-19) situation in the country.
Pollard, the director of the Oxford vaccine group, clarified that AstraZeneca is not working on a single-dose Covid-19 vaccine. Since both doses are needed to boost protection against coronavirus disease, it is understandable that in case of a vaccine shortage, better measures be instituted for the widest number of people instead of a smaller group. He pointed out that the UK only reduced the gap between two vaccines when a large part of its population was already vaccinated.
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The gap between the two shots matters because that's how the vaccine works. The first shot increases antibodies while the second shot is a booster one. If the second shot is delayed, the first shot gets more time to work. In April, Public Health England said the vaccine efficacy increases when the interval is 12 weeks. The United Kingdom also overcame the surge caused by the Alpha variant keeping the gap at 12 weeks.
Meanwhile, India has vaccinated more than 27 crore vaccine doses till now, the Union ministry of health and family welfare said on Friday. Nearly 30 lakh vaccine doses were administered till 7pm yesterday, while more than 5.2 crore vaccine doses have been administered in the 18-44 age group so far.