Serum Institute's Cyrus Poonawalla says mixing vaccine is a bad, bad idea

Cyrus Poonawalla, chairman of the Serum Institute of India, is opposed to the mixing of Covishield and Covaxin that is currently under proposal.

India's drug regulator had recently approved a study to be conducted by the Christian Medical College (CMC), Vellore on mixing of COVID-19 vaccines Covaxin and Covishield — to be tested on 300 healthy volunteers.

An expert committee of the Central Drugs Standard Control Organisation had recommended granting permission for the study.


There is no need to mix the doses, Poonawalla said, adding that if something goes wrong then there could be a blame game between the makers of the two vaccines.

If anything misfires, "Serum will say that the other vaccine is not good and they (the other vaccine company) will blame us claiming there was an issue with our vaccine."

"I think it is very wrong to mix the vaccines and you can quote me," Poonawalla said. Such a mixing is not at all proven in field trials, he warned.

Poonawalla made these comments at the Tilak Maharashtra Vidyapeeth in Pune.

The aim of the study is to find out if an individual can be administered two different vaccines, one part Covaxin and one part Covishield.

As per a recent ICMR study, 18 people in Uttar Pradesh who had an inadvertent mix-up of doses ended up showing "better immunogenicity than two doses of the same vaccine".

In the same study, it was also discovered that a combination of Covishield and Covaxin was safe, and that the adverse effects too were similar as a same-vaccine regimen.