New Delhi: The Centre on Wednesday said that there will be no mix-and-match of vaccines for those eligible to get a 'precautionary' third dose.
"Precautionary Covid-19 vaccine dose will be the same vaccine as has been given previously," said VK Paul, member-health, NITI Aayog, in a press briefing by the Union health ministry on Covid19 status and health system preparedness in the country.
This means those who have received Covishield as their first and second dose will receive Covishield as their third dose. Similarly, those who have received Covaxin in their first two doses will receive Covaxin in the third dose.
He, however, added that as the programme progresses and more data is available, there can be a review later.
The 'precautionary' dose - announced by Prime Minister Narendra Modi last month after sustained demand for vaccine boosters in the light of the Omicron threat - is, for now, only available for frontline and healthcare workers, and those over 60 with co-morbidities, starting January 10.
Calls for booster doses, at least for those who are at increased risk of contracting, or re-contracting, the virus, increased after the emergence of the Omicron variant, which is widely believed to be both more infectious and more resilient to existing vaccines.
The government's decision to not mix-and-match vaccines follows the World Health Organization saying it is advisable to ensure people get the same drug they were initially given.
In July last year the WHO's Chief Scientist, Dr Soumya Swaminathan, said mixing and matching vaccines was "a bit of a data-free, evidence-free zone."
Mixing and matching of vaccines should only be done if there is a supply constraint, the WHO said.
Vaccine combinations, already used by some governments, could help low- and middle-income countries manage stockpiles and deal with vaccine shortages as the Omicron variant spreads.
The European Union has endorsed the mixing of two different shots for both initial vaccine schedules and boosters, and the United States, in October, said it would allow 'mix-and-match' boosters.