The finding in Minnesota last week of the nation's first COVID-19 infection from a more contagious Brazilian variant is raising concerns that pandemic cases could accelerate, although more information is needed on the exact nature of the threat.
As with variants that have emerged in the United Kingdom and South Africa, scientists believe the strain spreads more easily and quickly than others, potentially sickening more people.
But health officials don't know for sure if it's spreading in Minnesota. The state Department of Health said last week that it identified the strain in a specimen from a resident who recently traveled to the South American nation. It's also not clear the extent to which immune system protection that's been stimulated by vaccines or a previous SARS-CoV-2 infection will work against the Brazil variant.
Worries over the variants come amid otherwise encouraging signs about the pandemic in Minnesota, with thousands of residents being vaccinated each day and a recent decline in new cases.
"We are in a very, very difficult period," said William Hanage, an epidemiologist with the Harvard T.H. Chan School of Public Health. "The variants of concern are ... serious causes of concern, but we don't know enough about them at the moment to be able to be definitive.
"And this is happening at a time when vaccines are beginning to become available and people are starting to feel like they're going to be able to relax. That's dangerous for a lot of reasons."
Minnesota reported on Saturday 1,087 new coronavirus cases and 19 more deaths due to complications from COVID-19. The seven-day rolling average for new cases fell to about 1,002 per day — the lowest reading since late September, according to the Star Tribune's coronavirus tracker.
The statewide tally for people who've received at least one vaccine dose increased by 35,568 in the latest data release, for a total of 381,204 people. That's about 6.7% of the state's population — up from 4% a week ago, according to Star Tribune estimates.
Variants are common as viruses replicate, changing over time as they gather mutations, said Sara Vetter, the interim assistant director of the state public health lab in St. Paul, during a briefing with reporters last week. Most mutations have no impact on the virus, Vetter said, but in some cases a group of mutations can change how a virus spreads or causes disease.
The Brazil strain is one of three "variants of concern" that the Health Department is watching closely, Vetter said.
"Although variants might have an impact on vaccine, it's not likely that a vaccine will be rendered completely ineffective," she said. "Also, if this virus continues to change and evolve, it's important to note that the mRNA vaccines, like Pfizer and Moderna, are easily adaptable and can be updated."
Earlier this month, Minnesota reported its first five cases of the B.1.1.7 variant that was first found in the United Kingdom. By Friday, the state's count had grown to 10 cases, according to the U.S. Centers for Disease Control and Prevention, which says there are now 434 cases across 30 states. Last week, South Carolina became the first state to find cases of the B.1.351 variant that's been linked to South Africa.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said at a press briefing last week that antibodies stimulated by the vaccines appear to work well against the B.1.1.7 variant while providing less, but still significant, protection against the South Africa strain.
"With P.1, we just don't know," Hanage said, using the scientific name for the variant linked to Brazil.
For now, the lack of certainty "should be a very strong impetus to get as many people vaccinated as possible," Hanage said. "Because in order to limit transmission, if your vaccine is less effective, you need to vaccinate more people in order to provide that fire break, which you get by vaccinating them."
It's not yet known whether the Brazil variant causes more severe illness, the Health Department says. It surfaced in Manaus, a city in the Amazon region where scientists estimate that a widespread SARS-CoV-2 outbreak last year infected about 75% of residents.
If many residents are now being reinfected, that could be a troubling sign that patients confronting the variant go "back to square one" in terms of immune system protection, said Dr. Priya Sampathkumar, an infectious disease specialist at the Mayo Clinic. It could be, however, that there's still some protection from the previous infection.
"What we don't know is: Are the reinfections as bad? Or, do people do better the second time around?" Sampathkumar said. "So, it's something that we need to watch and pay attention to."
It also underscores the importance of slowing transmissions in general, since "the fewer people who are infected with COVID, the less chance the virus has to do these mutations," she said.
While scientists are getting data that shows the U.K. variant is more transmissible and a bit more virulent, there isn't as much information on the Brazil variant, Hanage said. The fact that Minnesota found the variant in someone who recently traveled to Brazil is good news, he said, because it suggests it might not yet be spreading in the community. Even so, the relative lack of genomic sequencing of viruses in the U.S. also means it's likely the variant's spread isn't fully known.
As sequencing capacity increases across the U.S., "we expect more variants will be identified as this pandemic progresses," said Vetter, the assistant director at the state lab.
Health officials stress they do understand one key aspect of the Brazil variant — its transmission can be stopped by the same measures recommended throughout the pandemic, such as wearing masks and maintaining social distance. That means "this is a good time to double down on those efforts and try to prevent any spread, because we know spreading will be more efficient with these variants," said Dr. Mark Sannes, an infectious disease specialist at HealthPartners.
The Health Department reported Saturday that 105,361 people have now completed the two-dose series of vaccinations, up from 59,715 last Saturday.
Residents of long-term care and assisted-living facilities accounted for 11 of the newly announced deaths and 3,922 deaths since the start of the pandemic. Since the virus started infecting Minnesotans in March, the state has reported 460,819 positive cases, 24,269 hospitalizations and 6,187 deaths.
The state's one-day count of 1,087 new cases came on a volume of 32,732 newly completed tests. The recent trend on cases is encouraging, Sannes said.
"If we can keep our case numbers here down where they are right now, and continue to get our most vulnerable folks ... vaccinated," he said, "we are going to continue to see fewer hospitalizations and fewer deaths."
Christopher Snowbeck • 612-673-4744