Nearly a month after sewage surveillance in Bengaluru showed the presence of possible BA.4 and BA.5 sub-lineages of Omicron in some samples, the Indian SARS-CoV -2 Genomics Consortium (INSACOG) confirmed it on Tuesday.
According to INSACOG’s June 21 report, 44 samples sent for genome sequencing between June 2 and June 9 have been found to be infected with Omicron’s BA.3, BA.4, and BA.5 sub-lineages.
However, Omicron’s BA.2 continues to be the dominant strain in Karnataka so far. Of the 1,964 samples sequenced in May-June this year, 89.4% are found to be infected with Omicron BA.2.
While Delta was the dominant strain during the first wave with 90.7% of the 4,441 samples, sequenced from March 2021 to December 2021, found to be infected with it, 87.8% of the 6,099 samples, sequenced from January 2022 till April 2022, were found to be infected with Omicron.
Overall (all sub-lineages put together), 99.2% of the 2,215 samples sequenced in May-June 2022 have been found to be infected with Omicron. So far, a total of 12,755 samples have been sequenced in Karnataka.
Nascent phase
The presence of BA.2 sub-lineage of Omicron has increased from 80.6% in the first quarter (January to April, 2022) to 89.4% in May-June, 2022. Health and Medical Education Minister K. Sudhakar, in a tweet, said the presence of new Omicron sub-lineages - BA.3, BA.4 and BA.5 - are found to be in their nascent phases.
State Health Commissioner Randeep D. said surveillance will be intensified now to curb the spread in clusters. “Besides targeted testing of ILI/SARI cases, all primary and secondary contacts of positive persons, especially in clusters, and those in the high-risk group will be tested, irrespective of symptoms. We will also keep a watch on hospitalisations,” he said.
M.K. Sudarshan, chairman of the State’s COVID-19 Technical Advisory Committee (TAC), said, “It is time now to impose fines on violators of mask rule to prevent any further surges and contain the spread. We will meet and again recommend this to the State government”.
As the new sub-lineages are highly transmissible, masking up is the best weapon. “Besides, getting the precaution shot and following COVID-19 protocols is very important now,” he said.
Not alarming
Asserting that the situation is not alarming as of now, the TAC chairman said, “This is not the beginning of the fourth wave. The BA.4 and BA.5 sub-lineages of Omicron had been detected a month ago through sewage surveillance. It is only that INSACOG has confirmed it now and there is no doubt that the current surge is due to these sub-lineages.”
TAC member Giridhar R. Babu, who heads Lifecourse Epidemiology at Indian Institute of Public Health in Bengaluru, said it is now essential to continue monitoring clusters and at-risk populations needing hospitalisation.
“While precaution dose coverage should be increased for the vulnerable, especially senior citizens, it is also important to prevent reinfection as reinfections can also be devastating,” he said.
Earlier, before INSACOG had confirmed the new sub-lineages, Dr. Babu had tweeted: “Not finding #BA4/#BA5 does not mean that they are not responsible for the surge, at least in part. If indeed absent from everywhere, the cases might be many more when they indeed are present. Strengthening the surveillance mechanisms are necessary. Eventually #BA4,#BA5 and other sub-lineages will have to replace #BA2. Also, #reinfections are not without harm.”
