Vaccine booster, COVID-19 levels remain low in Minnesota

COVID-19 is still a global pandemic, but it is behaving like a stable endemic in Minnesota, where infections have declined slightly and hospitalizations and deaths remain constant.

Thursday's state COVID-19 update showed less than 800 infections per day in mid-October, compared to 1,400 per day in mid-August. Sampling at wastewater treatment plants showed declining viral levels in sewage in most regions as well, indicating the decline in infections is real and not just the result of less testing.

COVID-19 hasn't surged this month like it did in October the last two years, when a sharp increase in infections consumed hospital capacity by winter. Hospitals showed little sign of pressure this month: Minnesota has averaged 439 COVID-19 hospitalizations since June, and Tuesday's total was 438. The latest total included 52 patients requiring intensive care, though, up from 28 on Oct. 12.

"The virulence of the organism as well as the increased immunity in the population has helped," said Dr. Andrew Olson, a hospitalist at the M Health Fairview University of Minnesota Medical Center. "We still are seeing people who are ill and very, very sick from COVID in the hospital, but in a number that is relatively stable overall."

An estimated 88% of Minnesota children have already been infected with the coronavirus that caused COVID-19, according to the Centers for Disease Control and Prevention, which based the figure on a review of blood samples for medical tests. Infection rates run higher in children, but data suggest that many Minnesota adults have had COVID-19 as well and gained immunity temporarily.

Health officials have urged vaccination with the latest COVID-19 booster shots because immunity from prior vaccination and infection wanes within months. The latest boosters are formulated against the dominant strains of the coronavirus, and became available this week at state vaccination sites for children 5 to 11.

"The bivalent boosters were shown to be safe, and they produce antibodies against omicron, so they will be a crucial tool for protecting our state in the months ahead," said state Health Commissioner Jan Malcolm in a statement this week.

What's ahead is unclear. Sewage sampling reported by the University of Minnesota through Sunday showed a slight increase in viral loads in the Twin Cities area, but declining levels elsewhere. The U's metro data is based on 13 plants in towns such as Cambridge and Hastings. The Metropolitan Wastewater Treatment Plant in St. Paul reported an 8% decline in viral levels last week, with updated results due Friday.

Last fall's pandemic wave was fueled by the delta variant that increased the rate of COVID-19 deaths among younger adults, particularly the unvaccinated. Death rates have fallen since then among all age groups, but remain elevated among seniors. Of 64 COVID-19 deaths identified in October's first two weeks in Minnesota, 59 involved seniors.

State breakthrough infection data shows much less difference in infection and hospitalization rates among vaccinated and unvaccinated Minnesotans this fall, but health officials said they aren't surprised. Unvaccinated seniors during the delta wave were 17 times more likely to die from COVID-19 than fully vaccinated seniors who had also received boosters. Now, unvaccinated seniors are at 2.7 times greater risk.

Illness levels tend to even out between unvaccinated and vaccinated populations at times when viral levels are low or declining. Statistics for Minnesota's boosted population also include people who have waning immunity levels from shots they received months ago.

Demand for the variant-specific boosters has been tepid. While around 4 million Minnesotans 5 and older have received at least some COVID-19 vaccine, only about 520,000 doses of the latest boosters have been administered.

The federal Advisory Committee on Immunization Practices on Thursday voted to add COVID-19 vaccination to the recommended pediatric vaccine schedule. If the CDC agrees with the recommendation, states or school districts could decide whether to require the shots as conditions of enrollment.

Minnesota requires several pediatric vaccinations such as measles and tetanus shots, or written exemptions, before children can attend school. However, it doesn't require all shots on the federal list. Flu shots and pre-teen HPV shots are only recommended by the state.

Federal officials have raised concerns about two emerging viral subvariants, BQ.1 and BQ.1.1, that made up around 10% of U.S. coronavirus infections last week. Genomic sequencing of a sampling of cases in Minnesota has found just nine so far involving those variants. Other variants have presented similar concerns but didn't become dominant strains.

The new variants are being watched due to their rapid spread and ability to evade immunity from prior infection or vaccination. However, health officials hope the new boosters will offer protection because they are targeted against omicron variants and the new strains are part of that same viral lineage.