A coronavirus variant first detected in India has been designated a “variant of concern” by England’s public health body, as consternation about its spread within communities grows. The variant, called B.1.617.2 is one of three closely related variants that were first detected in India and have since been found in the UK, with the others known as B.1.617.1 and B.1.617.3. These variants have worried scientists as they have mutations in their spike protein that it is thought may help the virus to evade the body’s immune responses and be more transmissible. The variant B.1.617.2, also known as VOC-21APR-02, has caused particular consternation as its numbers have risen rapidly in the UK. On Thursday, the Guardian learned from leaked Public Health England documents that 48 clusters of B.1.617.2 had been identified, including those linked to secondary schools, care homes and religious gatherings, with evidence of community transmission in some of the clusters. The documents also revealed that the assessment of the ongoing risk to public health from this variant was “high”, while a leaked email sent by a staff member at the Department of Health and Social Care suggested the variant was poised to be upgraded from a “variant under investigation” to a “variant of concern”. Now PHE has confirmed the variant’s new designation, adding evidence so far suggests it is at least as transmissible as B.1.1.7 (the Kent variant), although its other characteristics are still being investigated. “We are monitoring all of these variants extremely closely and have taken the decision to classify this as a variant of concern because the indications are that this VOC-21APR-02 is a more transmissible variant,” said Dr Susan Hopkins, Covid-19 strategic response director at PHE, adding that the other two variants first detected in India had not been reclassified but that this would be kept under review. PHE has also released details of the number of cases of B.1.617.2 detected up to 5 May – figures that were due to be released on Thursday and delayed by what PHE called a “processing error”, but which the leaked documents said was because of the local elections. The figures suggest that cases of B.1.617.2 are on the rise, having increased from 202 to 520 over the last week, with about half the cases linked to travel or contact with people who have travelled. “The cases are spread across the country; however, the majority of the cases are in two areas – the north-west (predominantly Bolton) and London – and this is where we are seeing the greatest transmission,” PHE have said. According to data from the Wellcome Sanger Institute’s Covid-19 genomic surveillance, about 24% of Covid genomes in Bolton sequenced in the two weeks around 17 April relate to the three India variants, although the actual number of sequences per week was low and scientists warn the data can be “noisy”. PHE said it was working with a number of bodies, including local authorities and NHS test and trace, to “detect cases and limit onward spread”, with measures including surge testing and enhanced contact-tracing. Dr Simon Clarke, an associate professor of cellular microbiology at the University of Reading, said the development was not a shock. But he added: “It is particularly worrying that it has appeared in care homes, where residents can be expected largely to have been vaccinated. “While it seems that the vaccines may not have provided the level of protection against transmission that we may have hoped for, we still don’t know how well their protection against disease is maintained, but that will become apparent over the coming days and weeks. “We shouldn’t fall into the trap of thinking that protection against transmission is only a ‘nice to have’ because every new infection increases the risk that a new variant with a troublesome characteristic will be formed.”