Flu season arrives amid flat COVID-19 activity in Minnesota

Minnesota began weekly reporting of influenza Thursday as scheduled, amid concerns that even modest flu levels could combine with COVID-19 to increase illnesses and pressure hospitals.

The first weekly report showed three flu-related hospitalizations in Minnesota and no deaths or outbreaks in susceptible long-term care facilities. But low numbers are expected at this time of year — the flu season jumps after the holidays. The state averaged 4,300 hospitalizations and 250 deaths in the three flu seasons before the pandemic.

COVID levels remained stagnant as well, during a month when coronavirus infections surged over the previous two years. Minnesota is averaging fewer than 900 newly identified infections per day in October — significantly below the daily 1,300 to 1,400 cases this summer — according to the state's weekly situation update.

The 432 COVID hospitalizations Monday were about average for late summer, following a slight increase after Independence Day. COVID deaths have remained at about five per day, with Minnesota's pandemic toll increasing to 13,368.

Low but persistent COVID levels could present a challenge if they coincide with a typical flu season. Influenza was largely suppressed during the past two winters by the dominant spread of the coronavirus and the mask-wearing and social distancing practices used in response.

"Even if we can't predict exactly how the upcoming months will play out, we know both COVID and influenza will be circulating this winter, along with other respiratory diseases," said Dr. Ruth Lynfield, state epidemiologist.

"At a minimum, these infections can be disruptive, and in some cases they can cause serious illness or worse even among young, healthy people when there's not a surge or bad flu season."

Pre-pandemic levels of influenza have been detected in the Southern Hemisphere in recent months, meaning that similar levels are likely when the flu ascends north for the winter.

However, media reports predicting a severe season are at least premature and based largely on a rash of pediatric flu cases in Australia, said Michael Osterholm, director of the University of Minnesota's Center for Infectious Disease Research and Policy. The latest global surveillance is mostly finding low levels of influenza transmission.

"The Southern Hemisphere data for their 2022 does not support they had a bad flu season despite what the media has stated," Osterholm said.

Fatigue or hesitancy over COVID vaccinations could leave people more susceptible to either infection if they don't seek recommended shots. Annual flu shots are encouraged for anyone 6 months or older, unless they have specific allergies or other risks for adverse reactions. New high-dose flu shots are available and recommended for the first time this year for seniors.

New COVID boosters, formulated against the dominant strains of the coronavirus, are recommended to restore immunity in those 12 or older who have completed the initial series. New variant-specific boosters also were recommended this week for children ages 5-11, prompting Mayo Clinic and other health providers to briefly suspend scheduling of pediatric vaccinations with the old boosters.

The effectiveness of COVID vaccines has waned, largely because new viral variants have emerged to overcome vaccine-induced immunity. However, Thursday's state breakthrough report still shows a benefit: Unvaccinated seniors were three times more likely to die of COVID over the past two months — and four times more likely to be hospitalized — than those who had received boosters.

The high rate of immunity through vaccination and prior infections has reduced the public health risk in Minnesota somewhat, making it appropriate for entities such as the city of St. Paul to back off vaccine mandates, said Dr. David Boulware, a U infectious disease specialist.

However, Boulware said COVID vaccinations and boosters remain advisable even amid lower spread of the coronavirus. A secondary analysis of a U clinical trial on COVID treatments found in September that vaccinated people recovered faster from their infections.

"Even if one has been previously infected," Boulware said, "there are strong merits for why people should receive the booster vaccines."

Uptake has been slow. While 4 million Minnesotans have received at least one shot of COVID vaccine, only 8.2% are considered up to date, meaning they just completed the initial series or have received boosters.

Mayo Clinic's 14-day predictive model for the first time in weeks suggests a mild increase in COVID activity in Minnesota. Wastewater surveillance can be predictive as well, identifying changes in viral levels in sewage before they show up in increased illnesses and hospitalizations.

However, the latest statewide results are muddled, with viral loads increasing slightly in wastewater in some regions of the state but declining in others.

Wastewater analysis isn't planned to track influenza, which already is monitored through sentinel reporting clinics in Minnesota. Flu-like illness made up less than 2% of visits to these clinics in the week ending Oct. 8, which is typical at this point in the season. Flu-like illness usually peaks each winter with 6% or more of patients at these clinics.