A day after the UK reduced the gap between two vaccine doses from 12 to 8 weeks, India defended its decision to increase the window between Covishield doses, saying the call was based on science. Top independent virologists have also said that currently there is no study that shows decreasing the gap gives better immunity against the virus variant B.1.617.2.
Niti Aayog member (health) Dr VK Paul said, “The decision to increase the gap between doses was not expedience. It is a scientific decision. Science is evolving. SARS-CoV-2 science is 1 year 6 months old. We are continuously learning. Please accept this decision.”
India had increased the gap between two Covishield doses from 6-8 weeks to 12-16 weeks on Thursday after a recommendation from National Technical Advisory Group on Immunisation. The ministry of health and family welfare had said that the decision was taken after considering data from UK which had introduced a gap of 12 weeks between two AstraZeneca doses.
However, UK reduced the gap from 12 to 8 weeks on Friday citing the spread of B.1.617 variant of the virus that originated in India. Questions have once again been raised on whether the government had based its decision on scientific data or is trying to address vaccine shortage by delaying doses.
Paul said the 6-8 weeks gap for Covishield at the beginning of India’s immunisation drive in January was led by the fact that enough data wasn’t available to introduce a 12-week interval.
‘UK aims to push immune response’
“Our scientists felt that the risk of breakthrough infection (Covid infection between two doses) with a longer gap between doses is potentially higher,” Paul said. Scientists and public health experts have said there is no study to conclusively say that reducing the interval from 12 to 8 weeks would provide better protection against the mutant virus.
“The UK has no data that tells you that you have effectiveness against B.1.617 if you get two doses of the vaccine early, at eight weeks. What they are doing is looking at the immunogenicity data (indicating the type of immune response and magnitude) and the data available on the neutralisation of the virus. Their goal is to push up the immune response as much as possible — it’s a theoretical construct, and it’s not irrational,” says Dr Gagandeep Kang, professor at Christian Medical College, Vellore.
India will be in a better position to make its own evidence-based recommendations if we had any effectiveness data, says Kang, who is a member of the Covid-19 Working Group.
A Union health ministry statement had said the group agreed to increase the dosing interval in India to 12-16 weeks based on “available real-life evidence, particularly from UK”.
