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'BA.4, BA.5 subvariants causing COVID spike in Bengal': Experts sound caution


KOLKATA: Genome sequencing of Covid positive samples has revealed that Omicron subvariants BA.4 and BA.5 have started replacing the BA.2 alternative that caused the surge in cases of the infection in West Bengal earlier this year, a senior official of the state health department said on Thursday.

According to experts, it is mostly subvariant BA.5, which has features identical to BA.2, that is responsible for the recent spike in coronavirus cases in the state.

"We have been conducting genome sequencing on positive samples in West Bengal. A few subvariants of Omicron, mostly the BA.4 and BA.5 was found. But there is nothing to worry about. The BA.5 subvariant though highly infectious is not that threatening, at least for those who have no comorbidities," Siddhartha Niyogi, director of health services said on Thursday.

"Examinations of the samples showed that the subvariant BA.5 is gradually replacing the BA.2," he said.

Most of the Covid samples sent to National Institute of BioMedical Genomics in Kalyani for genome sequencing tested positive for the BA.5 subvariant of Omicron along with some BA.4.

Kheya Mukherjee, the associate professor of the department of microbiology at Beliaghata ID&BG Hospital held the Omicron subvariant BA.5 responsible for the recent surge in COVID cases in Bengal.

The state, she said, will witness more and more cases in the next few weeks as the infectivity rate of BA.5 is "much more" than its predecessor, the BA.2, she said.

"The steep rise in the number of Covid cases in Bengal is primarily due to this subvariant BA.5. There are cases where subvariant BA.4 is present. There are cases which are still caused by BA.2. I doubt how complicated BA.5 will be compared to BA.2 subvariant because most of the people are vaccinated. The infection will be mild and the fatality rate will be low as well," Mukherjee told PTI.

The microbiologist also predicted that the infection will scale up in the coming days and might reach a peak before receding.

"In the state, the contagion has almost doubled in just five days and it shows that there will be several thousands of infections in a day. It may reach a peak at one point of time and then start receding," she said.