Covaxin stirs nearly recovery-level antibodies

Pune: Antibody levels in Covaxin recipients — given both doses — more or less matched quantities that were generated by those (unvaccinated) who recovered after being sickened by newer virus variants, a study by the National Institute of Virology (NIV) has found.

Samples drawn from 146 Covid-19 cases were studied by the NIV; 15 of these samples had the variant with the double mutation — the B.1.617 (believed to be the one causing the Covid surge in the state).

Bharat Biotech, which manufactures Covaxin, and the Indian Council of Medical Research were also part of the latest study.

A scientist with the NIV said, “Serum samples were collected from recovered Covid patients who were infected with known SARS-CoV-2 versions out of South Africa and Brazil and those with the D614G mutation. The neutralization efficacy in these samples was tested against the double mutant or B.1.617. Serum samples of Covaxin recipients were also tested against this variant. After a comparison, we found that the neutralizing antibody levels in both types of serum samples were almost the same. This demonstrates that Covaxin can have the same ability in neutralizing the B.1.617 variant as that found in the serum of recovered Covid patients.”

Dr Samiran Panda, head of the ICMR’s epidemiology and communicable diseases division, said, “The mean antibody concentration in serum samples from a group of people who were earlier infected was almost similar to the mean antibody concentration in the samples of those vaccinated with Covaxin. These samples were effective against the double mutant. Therefore, instead of panicking, more people should get themselves vaccinated.”

The study noted a slight drop in neutralisation activity of Covaxin against the B.1.617 variant. It stated, “Similar results have been observed with serum samples of those who vaccinated with the Pfizer–BioNTech vaccine, which had effectively neutralized the UK and P.1 (Brazil) variants equally. But neutralization of B.1.351 (South African) variant was reduced in case of this vaccine as well, though found to be robust.

The study said that despite a drop in neutralizing capacity, the vaccines worked.

The research also said that symptomatic cases in the study had mild upper respiratory tract infection with low-grade fever, cough, and sore throat.

Fortunately, none of the cases developed severe disease and went on to recover completely.

“But the new variant has been associated with enhanced infectivity, transmissibility and immune-escape ability. The two mutations — E484Q and L452R—in the variant might enhance the transmissibility of the virus. But we need more studies on this,” the NIV scientist said.