There will be no mix-and-match of vaccines for the crucial third dose to be given in view of the Omicron variant that is rapidly spreading in the country, senior health ministry sources told NDTV today.
Precaution doses will be a third dose of the same vaccine a person has taken — be it Covishield or Covaxin. The key aspect will be gap — the third dose will be administered 9-12 months after the second dose to health and frontline workers and senior citizens with co-morbidities, sources said.
Experts are meeting today to chalk out the rollout process of the precautionary doses, which will be administered starting January 10.
There has been considerable debate worldwide over whether mixing vaccines or sticking to the same vaccine for the third dose offers better protection. While specific data from both are yet to come in for booster doses, mixing vaccines for the first and second shots is seen to have triggered a more robust immune response.
A key study from the UK into mixing COVID-19 vaccines has found that people had a better immune response when they received a first dose of AstraZeneca or Pfizer-BioNTech shots followed by Moderna nine weeks later, according to the results on Monday.
“We found a really good immune response across the board…, in fact, higher than the threshold set by Oxford-AstraZeneca vaccine two doses,” Reuters had quoted Matthew Snape, the Oxford professor behind the trial, as saying.
Recent studies at UK’s Oxford University showed that a third dose of the AstraZeneca vaccine — which is known in India as Covishield and accounts for nearly 90 per cent of doses administered in the country — significantly boosted neutralizing antibodies against Omicron.
The study also showed that immunity from the two doses that are currently being administered, starts waning after three months.
In view of this, a section of doctors and the Indian Medical Association had repeatedly asked the government to provide additional doses to front-line and health workers and people with weak or compromised immunity.
The number of cases of the fast-spreading Omicron variant has crossed 400 in India, with Maharashtra reporting the maximum number of infections.