Why the interval between first and second Covishield doses must now be shortened…??

Mansi Khandelwal, INN/New Delhi,


Later back in from last some days, we can see that the gap between the 2 doses of Covid-19 vaccine COVISHEILD is increasing and decreasing. The discussion is always on on this topic, and the people out there are very confused about the same.

The covid vaccine “covisheild” is given wide spread to the people in India and some other countries as well. The particular had 2 doses of it, out which first was said to develop antibodies, and the second one as the booster dose. Earlier these doses were given in the gap of 4-5 weeks or 45 days. But now the as studies are changing and the new variants are coming across the scientists they are continuously bringing the changes in the gap of the two doses. And according to the latest report the gap is extended to 12-16 weeks which is now again in discussion that this gap should be reduced as many countries and their experts have cast that this gap should be reduced, and this makes the Indian vaccine covisheild a contentious issue.

In all thes discussion the commom question arrising among the common people is “Why the gap is so important?”

So, the answer is it is the way the vaccine works on a system and against the virus. The first dose develops the antibodies and the left one is given as the booster dose. Earlier the gap was of 4-6 weeks but as the studies grew health oraganisation from England and other countries in UK said that the gap should be 12 weeks so that the first dose gets more time to work as it can give 65-80 % protection. But just a coulpe of days after India extended the gap, new studues emerged saying that the protection percentage is just 33-35 and 65-85.

When asked from Dr. NK Arora about the frequent changes in gap between the two doses of covisheild and if India will make the changes or not he said that the changes are according to the studies coming in feont of them the initial gap of 5-6 weeks was on the trial basis but now the studies are forcing to make changes, because the public health is the foremost concern of both government and the health institutions ” Initial studies on Covishield were very heterogeneous. Some countries like the UK went for a dose interval of 12 weeks when they introduced the vaccine, in December 2020.While we were privy to this data, when we had to decide our interval, we went for four weeks interval based on our bridging trial data which showed good immune response. Later we came across additional scientific and laboratory data, based on which after six weeks or so, we felt we should increase the interval from four weeks to eight weeks, since studies showed that vaccine efficacy is about 57% when it is four weeks and about 60% when it is eight weeks.

Covid-19 and the vaccination are very dynamic. Tomorrow, if the vaccine platform tells us that a narrower interval is better for our people, even if the benefit is 5% – 10%, the Committee will take the decision on the basis of merit and its wisdom. On the other hand, if it turns out that the current decision is fine, we will continue with it,”

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