Antibodies fall against Delta, may require booster: Experts

Pune: Recent findings by the Indian Council of Medical Research indicating lower levels of neutralising antibodies against the Delta variant in a small portion of Covishield recipients might just tip the balance in favour of a third booster shot, experts have said.

The ICMR study has indicated a 4.5-fold and 3.2-fold reduction in neutralising antibody levels against the Delta variant in those who were given one and two doses of Covishield, respectively, compared to an earlier SARS-CoV-2 version that had the D614G mutation (detected early last year).

Dr Samiran Panda, chief of the ICMR’s epidemiology and communicable diseases division, said, “These kinds of observations have the potential of informing immunisation programmes, including the possible need for a third booster dose.”

For the study, serum samples were collected from healthy individuals who had received one or two doses of Covishield. Samples were also collected from Covid-recovered patients who had received one or two doses. A fifth category of individuals from whom samples were drawn were breakthrough cases — people who had contracted Covid after vaccination.

Dr Pragya Yadav, a member of the research team, said the study indicated that serum of Covid-recovered participants and the breakthro- ugh cases had higher neutralising antibody titres compared to non-Covid participants. “This indicates that neutralising antibodies in the serum of individuals who had contracted Covid, in a way, worked like the first dose. A full vaccination schedule after that resulted in higher levels of neutralising antibodies.”