‘Don’t panic over Covid re-infection or BA.4, BA.5’

Dr Sanjay Pujari, expert member with the Indian Council of Medical Research (ICMR), also pointed out that even if antibody levels wane over a period of time, the T cells memory cells, that are primed for immune response to the virus, are responsible for preventing severe illness. “The evolution of SARS-CoV2 virus, in terms of lineages and because of its ability to escape immunity, has been challenging. The new sub-variants have had the highest escape potential to vaccination and hybrid immunity. Prevention of infection is the function of neutralising antibodies and while these wane, new sub-variants add to the ability to develop reinfections. The reason, however, for mild disease, is due to T Cell immunity,” he said.

According to a report from the University of Oxford’s Centre for Evidence Based Medicine, studies have suggested that a majority of people with COVID-19 develop a strong and broad T-Cell response and some have a memory phenotype which bodes well for longer-term immunity.

Dr Pujari further noted the Omicron variants and sub-variants largely involve the upper respiratory tract. An initial clinical study of patients detected with sub-variants in Pune showed that there was no requirement for oxygen or hospitalisation. Dr Rajesh Karyakarte, Maharashtra coordinator for genome sequencing, said that his team had coordinated the identification of BA.4 and BA.5 for the first time across samples in Pune and found there was no need to panic. He, however, advised that we keep a close watch on hospitalisation to track changes in virus behaviour or infective capacity.

The Omicron sub-variants BA.4 and BA.5 are circulating globally and have been associated with the fifth Covid wave in South Africa. Recently, the US and Europe have also reported the Omicron sub-variants. In India, the first case of the Omicron sub-variant was detected in Hyderabad through the genomic surveillance programme.