Covishield gap of 12-16 weeks based on scientific data: Health Minister

Union Health Minister Dr Harsh Vardhan on Wednesday said that the decision to widen the gap between two Covishield doses was transparent and based on scientific data.

The minister’s statement comes amid concerns over the extension of dosage gap from the earlier six to eight weeks to 12 to 16 weeks and allegations of the decision being a unilateral one.

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“The decision to increase the gap between administering two doses of Covishield has been taken in a transparent manner based on scientific data. India has a robust mechanism to evaluate data. It is unfortunate that such an important issue is being politicised!” Vardhan tweeted on Wednesday.

In his tweet the minister also tagged a statement by Dr NK Arora, head of the National Technical Advisory Group on Immunisation (NTAGI), who cites a study by the UK health regulator to argue that vaccine efficacy varied between 65 per cent to 88 per cent when the second dose is given at an interval of 12 weeks.

“This was the basis on which they overcame the outbreak due to the alpha variant…because the interval they kept was 12 weeks. We also thought that this is a good idea…scientific reasons to show that when interval is increased adenovector vaccines give better response,” he was quoted as saying in the statement.

“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 per cent-10 per cent, 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,” Arora said.

Arora also stated that the decision to increase the gap between shots to 12-16 weeks was taken without any “dissenting voice”.

A report in Reuters, however, counters this claim. Quoting three scientists including MD Gupte, former director of National Institute of Epidemiology, the report says that they only decided on increasing the interval to 12 weeks.

“Eight to 12 weeks is something we all accepted, 12 to 16 weeks is something the government has come out with…This may be alright, may not be. We have no information,” Reuters quoted Gupte as saying.

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NTAGI members Mathew Varghese and JP Muliyil also said that there was no discussion on the 12-16 week interval and the group had only recommended 8-12 weeks gap.

Arora also said that further discussions are underway whether India should revert to four or eight weeks interval for Covishield vaccine while the emerging evidence regarding efficacy of partial versus full immunisation is also being considered.