Genomic surveillance has revealed the presence in India of a coronavirus variant with a mutation designated E484 that can evade three antibodies and scientists say it should be monitored closely as the country rolls out Covid-19 vaccines.

Among over 6,300 novel coronavirus genome sequences deposited so far in an Indian database, the variant with the E484 mutation also observed in several other countries has turned up in only two patients in Maharashtra — at Raigad and Thane.

Scientists at the Institute of Genomics and Integrative Biology (IGIB), New Delhi, say the E484 variant looks “worrying” as studies have suggested that the mutation may allow the virus to escape three antibodies.

The viruses were isolated from the patient in Raigad on September 1 and from the patient in Thane on September 8. Researchers at the Tata Memorial Centre’s Advanced Centre for Treatment Research and Education on Cancer, Navi Mumbai, deposited the genomes in the database in December.

A single mutation that escapes multiple antibodies is a source of concern because vaccines are designed to generate antibodies to block viral entry into human cells and prevent the virus from making trillions of copies of itself and causing disease.

“No coronavirus mutations anywhere are so far known to escape vaccine-induced immunity,” Vinod Scaria, a doctor-turned-scientist at the IGIB, told The Telegraph. “But we need to watch out for such mutations.”

Emma Hodcroft, a researcher specialising in epidemiology and immunology at the University of Bern, Switzerland, has mapped the E484 variant’s emergence worldwide.

“This mutation has arisen multiple times in many places,” she tweeted earlier this week.

A study by microbiologist Jesse Bloom at the University of Washington, US, and his colleagues has suggested that the E484 mutation had emerged early in the pandemic — by the spring of 2020.

The independent emergence of a specific mutation at multiple geographic sites, Scaria said, may imply that the virus gains some biological advantage when it acquires those mutations. The capacity to evade antibodies is a potential advantage although its implications for Covid-19 vaccines remain unknown.

“Since no clusters of cases with the E484 variants have been observed so far, we still do not have insights into whether this could also make the virus more transmissible like the UK variant,” Scaria said.

The fast-spreading UK variant, marked by the mutation designated N501, enhances the capacity of the coronavirus to enter human cells and thus increases transmissibility. Eighty-two people in India have been found infected with the UK variant.

The emergence of the UK variant in India has amplified concerns that if containment and quarantine efforts are slack, it could trigger clusters of infections in specific locations and alter the course of India’s Covid-19 epidemic that has been steadily shrinking since mid-September.

In an independent study, Scaria and his colleagues have detected 19 coronavirus variants circulating in India with escape mutations that allow them to dodge antibodies. But each mutation appears to evade only one antibody.

Scientists are concerned about escape mutations because vaccines are designed to protect people by generating antibodies. If variants are able to evade antibodies, scientists speculate, they may continue to cause disease in vaccinated people.