Bihar chief minister Nitish Kumar has tested positive for Covid-19 on a day experts declared that omicron has become the dominant Covid-19 variant in the state.

They also said on Monday that the worrisome aspect was that the devastating delta variant that brought the second wave of the pandemic was still causing infections in the state.

Confirming that Nitish has caught the infection, the chief minister’s office said he was now “in home isolation on the advice of doctors and has appealed to everybody to follow Covid appropriate behaviour”. Thirty persons working at Nitish’s official residence tested positive.

Meanwhile, 4,737 new Covid-19 cases were detected in the state on Monday taking the total number of active cases to 20,938. “The spurt in Covid-19 cases in the state is due to the omicron variant. It is causing around 85 per cent cases. The rest is due to the Delta variant. We can say this on the basis of genome sequencing of samples that have come to us from different corners of the state,” Indira Gandhi Institute of Medical Sciences director N.R. Biswas told The Telegraph.

“However, the delta variant which became infamous during the second wave of the pandemic last year by causing infection in the lungs is still present and around 12 per cent cases are due to it,” added Biswas, currently in isolation after turning Covid-19 positive.

The state-owned IGIMS started its own genome sequencing facility 10 days ago. Its latest test of 32 samples received from different districts revealed that 27 were caused by the omicron variant; four by delta while one sample was inconclusive.

All these samples were of people with a travel history outside Bihar and turned positive after returning to their native places.

Meanwhile, Bihar witnessed the first death of a doctor during the third wave of the pandemic. Pramila Gupta — a former professor at the Patna Medical College and Hospital — succumbed to the virus on Sunday evening.