The Union health ministry said on Wednesday that a new “double mutant variant” of the coronavirus and “variants of concern” have been detected in 18 states in India. The ministry, however, added that the new strain has not been found in sufficient numbers to establish or explain the rapid rise in cases in some states.

“Genomic sequencing and epidemiological studies are continuing to further analyse the situation,” a statement said.

It further said that 771 “variants of concerns”, or VOCs, have been detected in 10,787 positive samples shared by states and Union Territories. “These include 736 samples positive for viruses of the UK [B.1.1.7] lineage,” the ministry said. “34 samples were found positive for viruses of the South African [B.1.351] lineage. 1 sample was found positive for viruses of the Brazilian [P.1] lineage. The samples with these VOCs have been identified in 18 States of the country.”

The Indian SARS-CoV-2 Genomic Consortia, or INSACOG, has been conducting genomic sequencing and analysing the circulation of Covid-19 viruses. The ministry said that the analysis of samples in Maharashtra now as compared to December last year showed that there has been a rise in “E484Q and L452R mutations”, which confer immune escape (when the immune system is not able to recognise and eliminate a virus or pathogen) and increased infectivity (the ability of a pathogen to establish an infection).

“These mutations have been found in about 15-20% of samples and do not match any previously catalogued VOCs,” the statement said. “These have been categorised as VOCs but require the same epidemiological and public health response of ‘increased testing, comprehensive tracking of close contacts, prompt isolation of positive cases & contacts as well as treatment as per National Treatment Protocol’ by the States/UTs.”

In Kerala, the N440K variant, which is also associated with immune escape, has been found in 123 samples in 11 districts, it said. This variant was found earlier in 33% of samples from Andhra Pradesh, and in 53 of 104 samples from Telangana, the ministry said, adding that it has also been detected in 16 other countries, including the United Kingdom, Denmark, Singapore, Japan and Australia.

On Tuesday, the health ministry had said that 795 people in India have been infected with the coronavirus variants that were first detected in the United Kingdom, South Africa and Brazil.

Till March 18, as many as 400 people in India had contracted these three mutant versions, which have now spread to dozens of countries. Of the 395 mutant virus cases reported since last week, at least 326 are from Punjab and have been identified as the UK variant.

The nearly 50% rise in cases of new strains came as many states in India are reporting a sharp surge in daily infections. There have been fears that new variants of the virus might be the reason for the increase in cases.

India on Wednesday registered 47,262 new coronavirus cases. With this, India’s tally rose to 1,17,34,058. The toll climbed by 275 to 1,60,441.

India has been witnessing a sharp rise in coronavirus cases in the past few weeks. Maharashtra registered 28,699 new coronavirus cases on Tuesday, taking the overall count to 25,33,026. The state’s toll rose to 53,589 as 132 more new deaths were recorded.

Mumbai’s civic body, the Brihanmumbai Municipal Corporation, banned Holi celebrations in public and private spaces amid the surge in cases. It said that strict action will be taken against those who flout the norms.