The first case of XE, a more transmissible Covid-19 variant, was detected in Mumbai on Wednesday, a civic health official said.
A case of the Kappa variant was also detected during a sero survey, the official said, adding that the results came in genome sequencing of 376 samples, the 11th batch of testing in the local genome sequencing lab.
As per the survey, the Omicron variant was found in 228 out of 230 samples (99.13 per cent cases) from Mumbai, he said.
The genome sequencing of 376 samples was conducted at the municipal Kasturba Hospital's Genome Sequencing Lab.
The condition of the patients infected with the new strains of the virus was not serious, the official said.
Mumbai on Tuesday reported 56 Covid-19 cases, which is a three-fold rise from the addition to the tally a day earlier, taking the infection count here 10,58,185, a civic official said.
The death toll remained unchanged at 19,559, while the recovery count rose by 36 to touch 10,38,356, leaving the metropolis with 270 active cases.
The official said the XE mutant appears to be 10 per cent more transmissible than the BA.2 sub-variant of Omicron. So far, BA.2 was deemed to be the most contagious of all the Covid-19 variants.
The XE variant is a mutation of the BA.1 and BA.2 Omicron strains, referred to as a "recombinant”.
As per the initial studies, the XE variant has a growth rate of 9.8 percent over that of BA.2, also known as the stealth variant because of its ability to evade detection.
The World Health Organization has said the latest mutant may be more transmissible than the previous ones.
Mangala Gomare, executive health officer of the BMC, told PTI that the woman who was found to have contacted the XE variant had arrived from South Africa and tested positive for coronavirus infection three weeks after arriving.
"She was asymptomatic and tested negative the next day," Gomare said.
The woman, who is a costume designer, was a member of a film shooting crew. She arrived from South Africa on February 10, 2022.
"She did not have any travel history prior to that. She had been vaccinated with both doses of the COMIRNATY vaccine," the official said, adding that she suffered from no co-morbidities.
On arrival in India she tested negative for Covid-19, but on March 2, she tested positive during routine testing. In the subsequent test, she tested negative.
She had been quarantined in a hotel room during this period.
As to whether it was the first case of the XE variant detected in India, BMC officials said they could not confirm this.