A new Brazilian variant of the coronavirus has made its first known appearance in the United States in a person who recently returned to Minnesota after travelling to Brazil.
The Brazil P.1 variant was found in a specimen from a patient who lives in the Minneapolis-St Paul area who became ill in the first week of January, the Minnesota Department of Health said today.
Epidemiologists are interviewing the person to obtain more details about their illness, travel and contacts.
There was no immediate indication that the variant was spreading in Minnesota.
Viruses are constantly mutating, and new versions – called variants – often emerge. Health officials are also worried about variants that were first reported in the United Kingdom and South Africa.
Researchers believe they spread more easily than the virus that has already sickened millions in the US and caused nearly 420,000 deaths.
The Brazilian variant was first identified in four travellers who were tested at an airport outside Tokyo, Japan. It contains a set of mutations that may affect its ability to be recognised by antibodies, according to the US Centres for Disease Control and Prevention.
The Minnesota Department of Health has a programme that conducts regular surveillance for variants, testing 50 random samples from University of Minnesota laboratories weekly.
State Health Commissioner Jan Malcolm said the new finding underscores the importance of testing as well as continued efforts to limit the spread of the disease.
US President Joe Biden today reinstated Covid-19 travel restrictions on most non-US travellers from Brazil, the UK and South Africa. Experts had predicted it was only a matter of time before the Brazilian and South African variants appeared in the US.
It makes sense that it would be first spotted in Minnesota, which has lab capabilities beyond those available in other states, Schaffner said. That means it may already be present elsewhere in the US, but simply hasn't been identified yet, he said.
The CDC has said that the UK variant may become dominant in the US by March. Although it doesn't cause more severe illness, it will lead to more hospitalisations and deaths just because it spreads much more easily, the CDC said, warning of "a new phase of exponential growth".
Scientists last week reported preliminary but troubling signs that some recent mutations may modestly curb the effectiveness of two current vaccines, although they stressed that the shots still protect against the disease.
And there are signs that some of the new mutations may undermine tests for the virus and reduce the effectiveness of certain treatments. Some tests suggest the South African and Brazilian variants may be less susceptible to antibody drugs or antibody-rich blood from Covid-19 survivors, both of which help people fight off the virus.
Health officials also worry that if the virus changes enough, people might get Covid-19 a second time. Reinfection is rare, but Brazil has confirmed a case in someone with the new variant who had been sickened with a previous version several months earlier.
"We know that even as we work hard to defeat Covid-19, the virus continues to evolve as all viruses do," Malcolm said in a statement.
"That's yet another reason why we want to limit Covid-19 transmission – the fewer people who get Covid-19, the fewer opportunities the virus has to evolve. The good news is that we can slow the spread of this variant and all Covid-19 variants by using the tried-and-true prevention methods of wearing masks, keeping social distance, staying home when sick, and getting tested when appropriate."
Some researchers have raised a concern that people who have already been infected with Covid-19 could be reinfected with the Brazilian variant.
If confirmed, "that would be disturbing", said Dr William Schaffner, an infectious diseases specialist at Vanderbilt University.
The CDC has reported at least 195 cases of the UK variant in the United States. Those reports have come from at least 22 states, including eight in Minnesota. The South African variant has not been discovered in the United States.
Last week, the World Health Organisation urged a greater effort to detect new variants.