Coronavirus infections have dropped sharply among pre-K-12 students in Minnesota, where state health officials on Thursday urged continued vaccination to slow the COVID-19 spread so that children can enjoy summer and an unrestricted start to school next fall.

Only 369 pre-K-12 student infections were reported in Minnesota in the week ending May 22, down from more than 1,000 per week in April. The decline matches other progress in the state — including a record low 3.1% positivity rate of recent COVID-19 testing — but is particularly important because this spring's pandemic wave was fueled by viral spread among children and teenagers who had limited access to vaccine.

Gov. Tim Walz noted the "incredible drop" in student infections during his appearance at the Minnesota Zoo on Thursday to promote vaccination and incentives — including free zoo passes — that are available to 100,000 Minnesotans who get their first shots this month. Walz said Minnesota shortened this spring's pandemic wave by quickly reaching a 50% vaccination rate, but he urged unvaccinated adults to push that rate above 70% and to seek shots for children 12 and older as well.

"Seeing families going back into the zoo, that's because Minnesota's effort around vaccinations — and the people of Minnesota's commitment to putting COVID behind us — is going strong," Walz said.

Children and teens are less likely to suffer severe COVID-19, having sustained only three of Minnesota's 7,437 COVID-19 deaths and none of the 10 fatalities reported on Thursday. But health officials said they can suffer lingering complications from infections and that their mobility spreads the virus to others who are at risk for severe COVID-19 illness.

People 19 and younger made up 16% of known infections in 2020 but 30% of Minnesota's reported infections last month.

Their impact on the spring wave was seen partly by the rise in sports-related outbreaks, which are defined as two members on one team suffering infections at the same time with no other transmission sources in common.

Outbreaks rose from 43 in January to 137 in April before declining to 65 in May.

Even if COVID-19 doesn't cause as much severe illness in children, "there is always spillover into other populations [and] collateral impact," said Kris Ehresmann, state infectious disease director.

"So in order to control COVID, we need everyone to take advantage of the vaccine."

Children 12 to 15 received access only to the Pfizer version of COVID-19 vaccine in mid-May. Since that time, nearly 80,000 children in that age range have received shots — exceeding the total of 64,040 recipients among teenagers 16 to 17 who have had access to the vaccine for a longer period of time.

Ehresmann said it is remarkable that 27% of people 12 to 15 have already received vaccine but that interest has started to taper off.

"Just remember that if you're not vaccinated, you're still at risk," she said. "Certainly the lower numbers help, but the virus certainly seeks out people that are susceptible. I just want to acknowledge that, even though we have a lot to celebrate."

Minnesota remains on track to reach a goal of providing vaccine to 70% of people 16 and older by July 1. The rate now is 64.7%.

Walz lamented that the 10 deaths reported Thursday were preventable through vaccination — although it is unclear whether those victims had received any shots. Minnesota has identified only 32 deaths from "breakthrough" infections in the nearly 2.5 million people who have been fully vaccinated — which means it had been 14 days since they received their final doses.

"All 10 of those were preventable … that's the part that haunts me," the governor said.

Minnesota had one of the highest infection rates in the U.S. during the latest wave, but its rate in the past seven days dropped to 20th among states.

The state on Thursday reported another 238 coronavirus infections, raising its pandemic total to 601,881.

The state on Thursday reached almost 10 million reported COVID-19 tests, which were performed on more than 4.2 million people.

Health officials remain concerned about the spread of more infectious variants of the coronavirus, even though infection and COVID-19 hospitalization rates have fallen below Minnesota's high-risk thresholds.

Vaccine appears protective against the more infectious B.1.1.7 variant of the coronavirus, first identified in England, that is responsible for roughly three-fourths of new infections in Minnesota. While the state has identified only 217 infections with the B.1351 variant first identified in Africa, and 306 infections with the P.1 variant first identified in Brazil, health officials have noted that those variants are causing an elevated rate of COVID-19 hospitalizations.

"Variants do remain an ongoing threat because they do have the ability to change and they do have the ability to adapt in a way that may not be covered by vaccines," Ehresmann said. "So we're continuing to watch that."

COVID-19 hospitalizations overall have declined in Minnesota — from a peak in the latest wave of 699 on April 14 to 252 on Wednesday.

All state mask requirements and social distancing and capacity caps on businesses have been removed, allowing places such as the Minnesota Zoo to begin to return to full activities.

The zoo maintained minimal operations over the past year, caring for animals thanks in part to 25,000 of 43,000 memberships being renewed, even if people couldn't visit, said John Frawley, zoo executive director. Children even emptied piggy banks to support the animals, he said.

"We're glad to be back in business. When I say we, I mean the animals, too," Frawley said during the governor's appearance. "They miss you, especially the primates and social animals. They love to see people. There are some that [couldn't] care less, that's true, but a lot of them really enjoy seeing the people back."

Jeremy Olson • 612-673-7744