Gov. Tim Walz and Minnesota Health Commissioner Jan Malcolm received second COVID-19 boosters on Wednesday and urged other vulnerable groups to consider the extra protection amid rising viral spread.

While second boosters have been available for a month, Walz and Malcolm said they sought their shots now before summer gatherings and to stretch immunity into next fall when new vaccinations or boosters could be recommended if the COVID-19 pandemic persists.

"Will we be boosted yearly? Will it be every six months?" the 58-year-old governor asked. "Those things are yet to be determined as we are learning more about the variants and where the virus is at. But it's absolutely clear that boosters are keeping people out of the hospital. They're reducing death rates."

Minnesota on Wednesday reported another 2,570 coronavirus infections, and closer examination of positive specimens showed a fast-spreading omicron BA.2 subvariant is causing almost all of the viral spread in the state. An even faster-spreading BA.2.12.1 subvariant is causing the nation's highest COVID-19 rates in the northeastern U.S. now, but it has been found in fewer than 20 cases in Minnesota so far.

The latest uptick isn't producing the same rate of severe illness and hospitalizations as other pandemic waves. COVID-19 hospitalizations in Minnesota declined from 305 on Monday to 286 on Tuesday, and only 22 people required intensive care. While both totals are above the recent low of 184 COVID-19 hospitalizations on April 12, hospital leaders said the latest admissions involve shorter stays and more patients whose infections are incidental to their primary medical needs.

"The ICU use, the most severe illness, is really very stable at a low level, and we are very grateful for that," Malcolm said, speaking outside her vaccination site at St. Paul Corner Drug.

The commissioner credited vaccinations for reducing severe illness as well as the new test-to-treat protocols in which people who test positive for COVID-19 can quickly receive antiviral or monoclonal antibodies therapies. Walz said rapid access aided his mother, who received treatment in Rochester shortly after testing positive for COVID-19 last month.

"That's the new way that we're managing this," he said, "and it's a very effective way."

Uptake of second boosters has been mixed since March 29, when the Centers for Disease Control and Prevention approved the additional doses of the Moderna or Pfizer COVID-19 vaccines for people who are older than 50, have weakened immune systems or have only received the less-effective Johnson & Johnson vaccine.

The number of doses administered in Minnesota almost tripled from 99,920 in March to 280,407 in April, primarily because people most vulnerable to COVID-19 wanted second boosters to maintain immunity against severe illness. Other eligible people chose to wait, noting the relatively low rate of severe COVID-19 and that the CDC permitted the second boosters but didn't strongly recommend them — other than to seniors.

Dr. Gregory Poland, one of the nation's strongest vaccine advocates and director of Mayo Clinic's vaccine research group in Rochester, said immunity wanes with time and many people are waiting for signs of more severe COVID-19 activity.

"The second booster is likely time-limited," he said. "So, the difficulty is not waiting too long and not jumping too fast so to speak."

Federal health officials said there are many circumstances in which a delay on a second booster would be appropriate, including a coronavirus infection in the past 90 days. Walz had COVID-19 in late December and was eligible by the time second boosters were recommended.

"We certainly encourage everyone to get vaccinated, get boosted, but these types of factors can be taken into account when deciding about your second booster dose," said Dr. Sarah Meyer of the CDC's National Center for Immunization and Respiratory Diseases in a news briefing late last month.

Minnesota reported three COVID-19 deaths Wednesday, raising the pandemic total to 12,515. The COVID-19 Forecast Hub, a collection of predictive models, forecasts more deaths and hospitalizations in Minnesota at least through mid-May, but the numbers are well below the peaks of prior pandemic waves.

The BA.2 subvariant isn't having as severe of an impact as earlier versions of the coronavirus, probably because there is so much immunity built up as a result of recent infections and vaccinations, said Michael Osterholm, director of the University of Minnesota's Center for Infectious Disease Research and Policy. New variants and waning immunity could change matters, though.

"Everybody is worried about omicron, which is understandable," he said. "I am worried about what is going to be pi or sigma or whatever is next."

Walz said vaccine benefits far outweigh risks of rare serious side effects, but he said there needs to be greater understanding of them. Both he and Malcolm urged more reporting to the federal Vaccine Adverse Event Reporting System, or VAERS, and more requests by doctors for closer evaluations of injuries following vaccinations.

More than 4.2 million Minnesotans have received a COVID-19 vaccine dose, according to the CDC. VAERS lists 17,890 reports of injuries following COVID-19 vaccinations in Minnesota, though that includes duplicates, injuries that end up having no relationship to vaccine and 10,000 cases that listed no medical attention.

"It is a very small percentage," Walz said, "but it matters."