INSACOG not right body to talk of herd immunity: Virologist

Talking to this reporter about INSACOG’s recent statement that herd immunity was now present among India’s population, he said herd immunity was different in animals and humans. “In fact, I had written to the European Journal of Epidemiology in 2000 that the term herd immunity should be redefined, and it was accepted,” he added.

The health officials in India were confusing herd immunity as defined by veterinarians, he said, adding that herd immunity cannot be applied to humans because unlike a herd of cattle, human beings are always in a state of flux. Herd immunity is possible only when the population is small and stays in one location without migrating, and the birth rate is very low. “This is not possible with humans,” Dr John said.

“What is of more concern for the public in the rapid Omicron spread is to know whether the Delta variant was still around, whether Omicron had replaced it, and whether Omicron had reached the endemic stage.”

Herd immunity is measureable and ICMR was going about this by its antibody surveys. Herd immunity was around 70 per cent at the end of the second wave and should be around 90 per cent now, he added. “In fact herd immunity starts from day one of the virus appearing when some are affected, some die and some are not affected.”