The contagious UK variant of COVID-19 has mutated again, in worrying genetic changes that may give the virus the ability to evade the immune system, according to scientists.

Public Health England reported that tests on some samples detected genomes with the E484K mutation, which has already been seen in the highly transmissible South African and Brazilian variants.

Calum Semple, a top scientist advising the UK government, told BBC radio that this “mutation of most concern” had developed spontaneously in the UK variant first detected in Kent in England’s south.

Sky’s science correspondent Thomas Moore said the “worrying development” meant the virus had effectively “developed a superpower” that enabled it to not only infect cells, but also to evade the immune system.

Research suggests the mutation may be more resistant to antibodies, although Moderna and Pfizer have claimed their vaccines are still effective.

Early testing by Moderna found its vaccine could protect against the mutation, although the effects may not be as strong or last as long. AstraZeneca is due to announce results on its vaccine’s effectiveness against the mutation this week.

UK Health Secretary Matt Hancock on Tuesday said a further 11 cases of mutations of concern had been identified in Bristol and 32 in Liverpool, warning of “renewed challenges posed by new variants of the coronavirus”.

At least 105 cases of the variant first identified in South Africa have already emerged in the UK, including 11 with no links to international travel: in parts of London, the West Midlands, east, southeast and northwest England.

Authorities in these areas have started offering door-to-door and mobile testing as part of a push to test 80,000 people for the variant, and are sequencing every positive test.

“In all these areas it is imperative that people stay at home and only leave home where it is absolutely essential,” Hancock said.