Herd immunity keeping India safe from BF.7 sub-variant

CHENNAI: The newly-emerged sub-variant is caused by the constantly mutating nature of the virus, however, the intensity and characteristics differ from region to region. While it has led to a surge in China with over 100 million cases expected, it is unlikely to trigger another wave in India.

"We had our share of Covid-19 cases and deaths since the time we had the first case of Covid in the country. Wuhan has only reported cases in 2020 in China during the first wave. They were successful in preventing the spread that year because of strict lockdown. Official records say that there was no outbreak in China that year, but India had a major outbreak. The first sero survey in India by ICMR showed that for every case there were 70-80 cases of infection. China had organised the Winter Olympics in 2021 and they practiced all safety measures, but it was not vaccination focused. It was this time that India had a delta wave and we also had reinfections. There were a large number of deaths," said senior virologist Dr T Jacob John.

He explains, "In 2022, we had Omicron variant and it was highly transmissible and multiple infections were reported in the country. We have a larger proportion of people with natural immunity or herd immunity in India. China lacked the herd immunity part and now the transmission is huge there. This is why the BF.7 variant is of not much concern to India."

BF.7 sub-variant is highly transmissible with a shorter incubation period which increases its capacity to re-infect individuals, including ones that are vaccinated. "It is believed to not be of serious risk due to our high levels of hybrid immunity among the Indian population. Individuals who received one or more doses of the vaccine had at least one SARS-CoV-2 infection either before or after the start of their immunization programme are said to have developed hybrid immunity," said Dr Spoorthi Arun, Internal Medicine, Promed Hospital.

"Further, new variants such as the XB.1.5 which are rising rapidly in the US have just been reported in India. These variant XB.1.5 appears to be getting around the antibodies built from Covid vaccines and from previous infections from various omicron strains, including the original BA.1 and the more recent BQ.1.1 and BQ.1 sub variants," said Dr Spoorthi Arun.

According to the INSACOG bulletin, BA 2.75 and BA 2.10 were also circulating but to a lesser extent. XBB is the most prevalent sub-lineage (63.2%) of the Omicron strain circulating all over India. “Especially, in north-east India, BA 2.75 is the prevalent sub-lineage. However, any increase in disease severity or hospitalisation has not been observed over this period,” it said.