Officials have identified the first UK cases of the Manaus variant of coronavirus, a new strain that may spread more rapidly and may respond less well to existing vaccines.

Public Health England (PHE) said on Sunday that up to six cases of the concerning variant first detected in the Brazilian city have been identified in Britain, three in England and three in Scotland.

The first two cases of the P.1 strain are from one household in South Gloucestershire with a history of travel to Brazil but the third is not linked.

The whereabouts of that individual is unknown, as PHE says the person did not complete their test registration card so follow-up details are unavailable.

Officials are asking anyone who took a test on February 12 or 13 and who has not received a result or has an uncompleted test registration card to come forward immediately.

Dr Susan Hopkins, PHE’s strategic response director for Covid-19, said: “We have identified these cases thanks to the UK’s advanced sequencing capabilities which means we are finding more variants and mutations than many other countries and are therefore able to take action quickly.

“The important thing to remember is that Covid-19, no matter what variant it is, spreads in the same way. That means the measures to stop it spreading do not change.”

The World Health Organisation has been informed of the cases, which have been designated “of concern” as it shares key mutations with the variant detected in South Africa.

More work is needed but there are concerns that the existing vaccines may be less effective against the Manaus strain.

In South Gloucestershire, one of the individuals had travelled back from Brazil in mid-February, before the Government introduced the quarantine hotel policy.

So they isolated at home with the rest of their household. One member developed symptoms, officials said, before getting a test.

There were three further cases in that household, two of which were confirmed as the Manaus variant with genetic sequencing, but the other two were not sequenced.

PHE and NHS Test and Trace are contacting the passengers on Swiss Air flight, LX318 travelling from Sao Paulo, through Zurich, and landing in London Heathrow on February 10.

The remaining unlocated case is not believed to be linked to the others because the virus was found to have slight genetic differences.

The Scottish Government said three residents who returned to north-east Scotland from Brazil, via Paris and London, subsequently tested positive for Covid-19.

The tests, completed in early February, were passed to the UK’s sequencing programme and were identified as being the Manaus variant.

Officials are contacting the other passengers on their flight from London to Aberdeen.

The cases are not thought to be connected to the three confirmed cases in England.

Scottish Health Secretary Jeane Freeman said: “The identification of this new variant is a concern but we are taking every possible precaution.

“This new variant demonstrates how serious Covid is and reinforces the need to minimise the spread of the virus.”