Mixing Covishield and Covaxin safe, provides higher antibody response


Mixing of vaccines — Covishield and Covaxin — is absolutely safe, says a recent study conducted by AIG Hospitals, one of India’s largest tertiary care centres, along with researchers from the Asian Healthcare Foundation. The study results show that mixing of Covid vaccines provide a higher antibody response as well.

The pilot study, conducted to determine the safety profile of mixing the two vaccines, showed that none of the participants developed any adverse effect.

High seropositivity

A total of 330 healthy volunteers who were not vaccinated and had no history of Covid infection were selected and screened for SARS-CoV-2 antibodies for the study. Of these, 44 (nearly 13 per cent) were found to be seronegative — they did not have Covid-related antibodies.

Also see: Children below 15 years will also be immunised: NK Arora, NTAGI Chief

“One of the incidental findings of the study is seropositivity among our population. Nearly 87 per cent of participants who didn’t get vaccinated and never tested positive for Covid had Covid-related antibodies. This means our population might have developed significant antibodies against Covid because of the huge delta wave that we endured,” Dr D Nageshwar Reddy, Chairman, AIG Hospitals, said in a press statement.

The 44 participants were divided into four groups. In two groups, participants were given first and second dose of the same vaccine (Covishield or Covaxin) while in the other two, different vaccines were given and antibody titers were checked.

“All these 44 participants were followed for 60 days to see if there are any adverse effects. The study conclusively showed that mixing of vaccines was absolutely safe as none of the participants developed any adverse effect,” said the press statement.

Spike-protein neutralisers

The most important finding of the study was that the spike-protein neutralising antibodies found in the mixed vaccine groups were significantly higher than the same-vaccine groups.

According to Reddy, who is among the researchers involved in the study, spike-protein neutralising antibodies are the ones which kills the virus and reduce the overall infectivity.

Also see: T cells come to the rescue as studies show they buck Omicron Covid variant

“We found that when the first and second dose are of different vaccines, the spike-protein antibody response is four times higher compared to two-dose of same vaccine,” he said.

Booster doses

This is particularly important when considering the third booster dose. The concept of a booster is to elicit robust antibody response. Mixed doses will enhance the vaccines’ effectiveness even against the Omicron variant, he added.

AIG Hospitals has shared the data from the study with the ICMR (Indian Council for Medical Research) to be considered as a reference study while deciding on the “Prevention” doses starting January 10.

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