Pune: Serum Institute of India (SII) chairman Dr Cyrus Poonawalla is opposed to the mixing of Covishield and Covaxin that is currently under the proposal.
Poonawalla, whose firm makes the Covishield vaccine, was speaking to reporters on Friday after receiving the Lokmanya Tilak National Award in Pune.
"I am against the mixing of two different vaccines. There is no need to mix two different vaccines," he said when asked about a recent ICMR study that a cocktail of Covishield and Covaxin could generate better immunity.
"If cocktail vaccines are administered and if the result is not good, then SII may say that another vaccine was not good, vice versa, the other company might say that since you mixed Serum's vaccine, it did not give desired results," Poonawalla said.
Clarifying his earlier statement, the SII chairman said, "For those who have been administered the first dose of a particular vaccine and in case of the unavailability of the second dose of the same - as an alternative, another vaccine can be administered. That said, the efficacy and the immunogenicity of the combination are dependent on the ongoing studies conducted by regulators."
A study by the Indian Council of Medical Research involving 98 people, 18 of whom had inadvertently received Covishield as the first dose and Covaxin as the second in Uttar Pradesh showed that combining vaccines elicited better immunogenicity.
According to the study, the findings have an "important implication" for the Covid-19 vaccination programme wherein "heterologous immunisation will pave the way for induction of improved and better protection against the variant strains of SARS-CoV-2".
The researchers have said such mixed regimens will help to "overcome the challenges of shortfall of particular vaccines" and "remove hesitancy around vaccines in people's mind that could have genesis in programmatic 'errors' especially in settings where multiple Covid-19 vaccines are being used".