The Indian government has denied that it doubled the gap between the two doses of the AstraZeneca Covid-19 vaccine without the agreement of their expert scientific panel, saying that the decision was “based on scientific data”.
Following reports that members of their expert committee did not agree to this decision, India’s health minister Dr Harsh Vardhan tweeted on Wednesday: “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!”
On Tuesday, a report by Reuters quoting three members of India’s National Technical Advisory Group on Immunisation (NTAGI) said the government’s decision to increase gaps was not based on the group’s advice, as it had claimed.
Three members of the 14 member group told the news agency that the body did not have enough data to make such a recommendation.
Narendra Modi’s government announced the decision to change the gap for Oxford-AstraZeneca vaccine -- labelled as Covishield in India -- from 6-8 weeks to 12-16 weeks last month. The decision was made when India was struggling with an acute shortage of vaccine doses, and as a deadly second wave crippled the country’s health infrastructure.
The government said the decision was based on “real life” data released by Public Health England. The Health Minister’s statement cited a study by PHE which showed “vaccine efficacy varied between 65 per cent - 88 per cent when the interval is 12 weeks”. However, the PHE later said that the protection offered by one dose of the vaccine could be considerably lower than previously thought, particularly against the B.1.617 (Delta) variant which caused India’s second wave.
MD Gupte, a former director of the state-run National Institute of Epidemiology, said the NTAGI had backed increasing the dosing interval to 8-12 weeks - the gap advised by the World Health Organization. But he added that the group had no data concerning the effects of a gap beyond 12 weeks.
According to Dr Naveen Thacker, president-elect of International Pediatric Association (IPA) and formerly CSO representative to Global Alliance for Vaccines and Immunisations (GAVI) board, the government should have clarified their position on the reasons for the decision to double the gap between doses.
“The decision by the government should have been communicated better,” he said. “There is evidence that increasing gaps to 12 weeks and more increases the efficacy, but the decision came at a time when the questions about vaccine availability were raised. It is mainly an issue of communication.”
“The evidence that efficacy increases by delaying the second dose has been there for some time, but the government did not increase the gap earlier... they increased it only when they ran out of vaccines,” Dr Sumit Ray, health expert and head of critical care at Delhi’s Holy Family hospital, told The Independent.
“If you balance the good immunological response and the need to vaccinate a large number of people quickly, a gap of about eight weeks, would be ideal,” he added.