A viral variant has become a dominant source of COVID-19 in Minnesota, causing as many as 65% of new infections and driving the state's case and hospitalization rates to some of the highest in the U.S.

A sampling of patients infected with the corona­virus that causes COVID-19 has identified 943 with the B.1.1.7 variant, which proved when it was found in England to be 50% more contagious and cause a 64% higher death rate.

The genetic ancestry of the variant cases showed that B.1.1.7 emerged earlier in Minnesota than originally known — perhaps in December when its existence was first reported in England, said Dr. Ruth Lynfield, state epidemiologist.

"I am worried about the spread of B.1.1.7, and I really urge Minnesotans to be patient and to continue to mask and continue to socially distance and continue to roll up their sleeves to get vaccinated," she said. "I do feel like we're at a critical juncture."

Minnesota has become an epicenter of pandemic activity this month — ranking 12th highest among U.S. states for its new infection rate in the latest White House COVID-19 report and 15th for its hospitalization rate. Michigan and northeastern states also are seeing increases.

Minnesota, on the other hand, ranked 36th for its lower rate of COVID-19 deaths in the seven-day period ending March 26. Health officials hope that's a reflection of an aggressive vaccination campaign that has protected people most at risk.

"It does feel like a race of people getting vaccinated against the variant," Lynfield said.

The state on Thursday reported that 1,682,545 Minnesotans 16 or older have received at least a first dose of COVID-19 vaccine, representing 38% of that eligible age group. Of them, 1,057,848 people have completed the one- or two-dose series. And 81% of senior citizens have received vaccine — a key risk group that has suffered 89% of Minnesota's 6,860 deaths.

Minnesota on Thursday launched its eighth vaccination site, in Oakdale, that will supplement clinics, pharmacies and local public health events. Access was expanded this week to all 4.4 million Minnesotans 16 and older, but many providers are still focusing on priority groups of seniors, health care workers, long-term care residents, educators and non-elderly adults with complicating health conditions or high-risk occupations.

Minnesota is expecting a boost next week of 80,000 doses of the single-dose COVID-19 vaccine made by Johnson & Johnson. The state is waiting for federal confirmation but does not expect disruptions, despite batches being discarded due to quality problems in a manufacturing plant in Baltimore, said Kris Ehresmann, state infectious disease director.

Sen. Amy Klobuchar on Thursday urged people at greatest risk of COVID-19 to seek shots. She visited a vaccine clinic operated by Gillette Children's Specialty Healthcare in St. Paul for disabled patients at elevated risk of severe COVID-19 and their caregivers.

"Remember, every shot is one step closer to having things go back to normal — restaurants, barbecues, Twins games and the like," Klobuchar said, "but I don't want this moment to go without knowing how difficult it is for families that have children with rare diseases."

Mark Brull of Edina had been vaccinated earlier but said he had struggled to find vaccination opportunities for his wife and 16-year-old daughter, Maya, who is vulnerable to severe COVID-19 because she has intractable epilepsy.

A previous bout of pneumonia left the teenager intubated for six weeks, and COVID-19 illness could cause severe symptoms or increase the frequency of her epileptic seizures, her father said. Obtaining vaccine for her at the Gillette clinic earlier this month was emotional.

"[I was] laughing and crying at the same time," Brull said, "that there is hope and there is a future and there is a sense of protection."

Minnesota on Thursday reported 2,140 more SARS-CoV-2 infections — the first daily count above 2,000 since Jan. 10. That raised the state's total to 521,667 known infections. The state also reported 12 more COVID-19 deaths.

The number of Minnesota hospital beds filled with COVID-19 patients increased on Wednesday to 435 — including 105 patients in intensive care. Hospitals are reporting younger patients compared with late last year, though, and a decline in deaths.

The increase comes amid a loosening of restrictions designed to slow viral spread, including the return of fans in professional sporting events this month. Widespread vaccination and sharp declines in COVID-19 deaths also prompted a loosening on Thursday of more restrictions in long-term care facilities. Residents this Easter weekend can leave for 24 hours and return without quarantining, regardless of whether they have been vaccinated, if they didn't come in close contact with anyone who had COVID-19, according to the new guidance.

Health officials urged continued prevention efforts beyond vaccine because of the variants. In addition to B.1.1.7, the state found a third infection involving a P.1 variant first identified in Brazil in someone who had traveled out of state. More infections involving variants found in California and South Africa also have been identified.

The state on March 5 warned of a B.1.1.7-driven outbreak linked to youth sports in suburban Carver County, but Lynfield said the latest evidence showed that the variant was spreading in other pockets of Minnesota by then.

Carver County officials responded with a recommended two-week pause on youth sports and increased COVID-19 testing. After that, exponential COVID-19 growth in that region switched to steady growth, Lynfield said. The outbreak has been linked to 189 infections.

"I do think the measures made a difference," she said. "This is a very contagious variant — we estimate 50% more contagious — than the regular strains. And so I do think we may have seen a lot more cases" if those measures hadn't been put in place.

Jeremy Olson • 612-673-7744