LONDON — The British government was hunting on Monday for someone whose Covid-19 test sample came back positive for a concerning variant of the coronavirus first detected in Brazil, one of the first known instances of that variant in Britain.
But the person’s identity and whereabouts were a mystery: The person neglected to fill out an information card that accompanied a test kit, sending British officials on a frantic quest to use postal service data to track them down.
Nadhim Zahawi, the government minister overseeing Britain’s vaccination campaign, resorted to asking anyone who was tested for the coronavirus on Feb. 12 or 13 in Britain but who did not receive a result to call a government hotline.
The appeal was an attempt to use all avenues to “make sure we locate them as quickly as possible,” Mr. Zahawi said on Monday on a BBC morning show.
The unidentified person was one of six British cases of the variant first seen in Brazil, known as P.1, that were announced on Sunday night. Two of the cases, in England, emerged in a household with someone who had recently traveled to Brazil. Three unrelated cases turned up in Scotland in people who had also recently returned from Brazil.
English and Scottish officials said they were tracing those people’s contacts, including fellow airline passengers. But for the moment, contact tracing was impossible for the sixth case.
In Brazil, the P.1 variant is believed to be responsible for cases of people who were previously sick with earlier versions of the virus becoming reinfected. It has several concerning mutations in common with the variant first detected in South Africa. That variant is known to have some degree of resistance to the immunity that people develop after recovering from an infection or being inoculated, though the variant first seen in Brazil is not believed to be quite as problematic.
It is possible that the P.1 variant is also more contagious, but that remains unclear, British government scientists have said. The variant has been reported in 25 countries, including the United States.
For Britain, most of the concerns so far have revolved around the variant first detected in southeast England, known as B.1.1.7, that is believed to be more contagious and deadlier, but not necessarily resistant to vaccines.
Asked on a radio program on Monday morning about how concerned people should be, Danny Altmann, a professor of immunology at Imperial College London, said: “Somewhat worried, but not total panic, perhaps.”