COVID-19 hospitalizations in Minnesota reached a 2021 high of 800 on Tuesday as a fourth pandemic wave continued to put pressure on the state's health care systems.

The Minnesota Department of Health on Wednesday also reported 31 COVID-19 deaths and 2,077 newly diagnosed coronavirus infections, raising the state totals in the pandemic to 8,140 COVID-19 deaths and 708,220 infections.

The state has reported 228 COVID-19 deaths so far in September, compared with 154 in August and 54 in July. While seniors make up 87% of Minnesota's COVID-19 deaths — and 28 of the deaths reported Wednesday — the latest update included a Hennepin County resident in the 35-to-39 age range. Eighty people younger than 40 have died of COVID-19 in Minnesota since the start of the pandemic 19 months ago.

Deaths and hospitalizations increased a few weeks after coronavirus infections peaked in three previous COVID-19 waves in Minnesota. Whether the latest wave has peaked is unclear, though.

The state on Wednesday reported a 6.6% positivity rate of recent COVID-19 diagnostic testing, above the state's 5% caution threshold for substantial viral spread but below a high of 7.1% last week.

While that could indicate progress, the Centers for Disease Control and Prevention on Wednesday provided an updated Ensemble model forecast for Minnesota that predicted no change in coronavirus infections through mid-October.

AARON LAVINSKY • aaron.lavinsky@startribune.com, Star Tribune

Mayo Clinic's 14-day forecast predicts a modest increase in the infection rate in Minnesota even as Southern states see declines following severe surges in COVID-19 activity this summer.

State health officials encourage unvaccinated Minnesotans to seek shots against COVID-19 and fully vaccinated residents to seek booster doses if eligible. The state last week followed federal guidance and advised third booster doses for people who received the Pfizer vaccine who are older than 64 or older than 49 and have underlying health conditions.

Boosters also can be given to people 18 or older with underlying conditions or increased risk of workplace viral exposure. Recommendations about boosters for the two-dose Moderna and single-dose Johnson & Johnson vaccines are pending.

Minnesota's first-dose vaccination rate is 74.6% among eligible residents 12 and older, according to the CDC.

Observational data from health care providers continues to match studies showing that the COVID-19 vaccine remains somewhat protective against infections but highly protective against severe illness and hospitalization.

Minneapolis-based Allina Health reported that 30% of its 198 COVID-19 hospitalizations on Monday were fully vaccinated. However, only 16% of its 32 COVID-19 patients on ventilators were fully vaccinated.

Health officials are concerned that deaths are still occurring in a senior population with a more than 90% vaccination rate. This could reflect a less robust response to the vaccine in the first place or waning immunity in an age group that received earliest access to the shots last winter.

Deaths in fully vaccinated people remain rare, though. The 160 COVID-19 breakthrough deaths identified in Minnesota so far make up 0.004% of the more than 3.1 million fully vaccinated people in the state.

Jeremy Olson • 612-673-774