Up to six cases of a highly transmissible variant of coronavirus first identified in the Brazilian city of Manaus have been detected in Britain for the first time.
Three cases were found in England and another three in Scotland.
Two of three cases found in England were from a household in the South Gloucestershire area that had a history of travel to Brazil.
A third, currently unlinked, case has yet to be identified, Public Health England said on Sunday.
The risk to the wider community from the Gloucestershire cases was considered low but as a precaution officials were moving quickly to deploy testing and increasing the sequencing of positive coronavirus samples from the area, PHE said.
The Scottish cases were not linked to the ones in England.
The P1 variant detected in Manaus shares some mutations with a variant first identified in South Africa and it is possible that it might respond less well to current vaccines, PHE said.
Susan Hopkins, PHE’s strategic response director for COVID-19, said Britain’s advanced gene sequencing capabilities meant it was finding more variants and mutations than many other countries.
Late last year Britain detected a more transmissible variant of coronavirus that is believed to have originated near London and that led to a sharp rise in cases in the country and beyond.
“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,” Ms Hopkins said.
PHE and test and trace officials system were following up with all passengers on Swiss Air flight LX318 from Sao Paulo to London via Zurich, which landed at London Heathrow on February 10, to test them and their households.
All three of the Scottish cases were identified in people who returned to the country via Paris and London who self-isolated for the required period of 10 days.
“Due to the potential concerns around this variant other passengers on the flight used by the three individuals from London to Aberdeen are being contacted,” the Scottish government said.