COVID-19 in MN: Caseload rise may be leveling off; ICU needs low, stable

COVID-19 cases continue to trend up but statewide wastewater data shows some hopeful signs that trend is throttling back. COVID hospitalizations are up, but the number of intensive care admissions and deaths remain low.

Minnesota down to 1 high-risk county

On Friday, the Centers for Disease Control and Prevention listed 66 of Minnesota’s 87 counties as having low community level risk for COVID-19, even while 53 are listed as high transmission areas.

This seeming paradox has much to do with the fact that while cases and hospitalizations are both on the rise, the COVID-related demand for hospital beds remains relatively low.

The updated CDC COVID-19 community level risk rating changes include a shift for Olmsted and Wabasha counties from high to medium risk. Pennington County in the state’s northwest corner currently has the only high community level risk rating in Minnesota.

Upward trend in wastewater may be leveling

The latest wastewater analysis from the Metropolitan Council and the University of Minnesota’s Genomic Center shows the COVID load rose 21 percent last week compared to the prior week.

As noted in the graph below, however, the data leveled off for three consecutive days during the past week and seems to have settled nearer the 200 million copies per day per person range, rather than the much higher 300 million range of some recent spikes.

That may be good news, and it lines up with some preliminary data from elsewhere in the state.

COVID-19 levels in metro wastewater

The genomic center’s analysis shows that omicron subvariant BA.2 continues as the dominant strain, now making up “about 97 percent of the SARS-CoV-2 RNA in Metro Plant influent” according to the Metropolitan Council. Included among that percentage is the sub-lineage BA.2.12.1, which now accounts for 18 percent of the area’s viral load.

Researchers also detected “the presence of omicron BA.4 and/or BA.5” in the sample taken on April 29. These newer subvariants have driven a high rate of COVID-19 reinfection in South Africa.

The University of Minnesota is also involved with a second, more expansive, wastewater SARS-CoV2 surveillance study that includes plants throughout the state and covers 60 percent of the population. It verifies that COVID levels are up in Twin Cities region wastewater testing as well as all other regions of the state.

As shown in the table below, From April 20 to 27 measured COVID-19 levels grew by at least 50 percent in all regions and more than doubled in the northeast and southwest regions.

On a more hopeful note, preliminary data from the surveillance study suggests that COVID-19 virus loads have leveled off in all regions this week, after falling in five of the regions.

That data is subject to change, but does corroborate the recent leveling off of COVID-19 in the Metropolitan Council’s wastewater data. 

Another case of increasing cases

As noted above, the CDC now lists 53 of Minnesota’s 87 counties as high COVID-19 transmission areas, along with one-third of all U.S. counties.

High transmission areas are those with 100 or more cases per 100,000 over the preceding week. Most of the rest of Minnesota’s counties, 22, are rated as having substantial transmission (from 50 to 99.9 weekly cases per 100,000). Eleven are moderate, and only Watonwan County in southwestern Minnesota is listed as having low transmission.

Minnesota is not alone in exceeding the CDC’s high transmission threshold. As shown in the graph below, that has also been the case for the U.S. as a whole as well as neighboring Wisconsin for the past couple of weeks.

Around two weeks ago case rates in both Minnesota and Wisconsin took off even faster than the national rates. Officially reported cases in our three other border states remain well below the national rate.

Since April 10, the state’s COVID-19 rate has exceeded the Minnesota Department of Health’s high risk designation of 10 new cases per 100,000 residents. As of MDH’s latest reading, April 27, the rate has climbed to 23.7 per 100,000.

The figure below shows that all regions are now above the state’s high risk threshold, and that rates are highest in Hennepin and Ramsey counties, the surrounding suburban counties of the Twin Cities metro, the southeast and the northeast.

COVID-19 case rates by region in Minnesota

Hospitalizations

Fortunately, intensive care unit admissions — the harshest hospitalizations — remain fairly rare, bouncing around between two and five new admissions for most of the past five weeks. Non-ICU hospital admissions continue to rise, though, now exceeding 40 per day.

Recent COVID-19 hospital admissions in Minnesota

Hospitalizations, of course, trail initial infections, but so far the Minnesota Department of Health puts the state’s COVID-19 hospitalization rate, 5.8 per 100,000, in the caution zone as opposed to the high risk characterization of our current case rate.

There may be some indication that the current wave of COVID-19 is less prone to serious outcomes — hospitalizations and deaths — than we have seen in previous waves. While these are just three previous dates, both ICU and non-ICU admissions are consistently higher.

While reported deaths are not yet available for late April 2022, the seven-day average has not exceeded 4 deaths since late March. Even better, preliminary data suggests Minnesota may have finally had another zero COVID deaths day on April 22nd.

Also note that the relative likelihood of hospitalizations and death may be even lower in this wave than the data above suggests. This is because while actual rates of COVID-19 are always higher than reported case rates (due to asymptomatic cases) that discrepancy may now be larger than ever. This is due to a possible rise in asymptomatic cases with recent variants and the proliferation of in-home-tests.

According to CDC numbers, the seven-day moving average number of officially reported tests in Minnesota associated with the dates above are 32,315; 37,885; 25,462; and on April 27 14,760. While the federal government now only requires reporting of positive tests, the ever-changing testing environment makes precise comparisons difficult.

Together with mounting national and international findings, this local data suggests that while more transmissible, omicron and its subvariants are less deadly than previous COVID-19 variants.

Vaccination rates: Room for improvement

Sixty-nine percent of Minnesotans are fully vaccinated, ranking 18th nationally. Thirty-nine percent have received a COVID-19 booster, which ranks 6th nationally.

As shown in the map below, the vaccination rate remains below 60 percent in 24 counties, even when excluding those below the age of 5, who are still ineligible at this point.

COVID-19 vaccination rates by county in Minnesota

The final graph in this week’s update demonstrates both the waning effectiveness of the original vaccination and virulence of the recent omicron strains. Most recently, Minnesotans who are vaccinated are just as likely as those who are unvaccinated to get COVID-19.

On the other hand, unvaccinated Minnesotans remain at least twice as likely to either get hospitalized or die from COVID-19 than is the case among those who are vaccinated.

Ratio of vaccinated and unvaccinated COVID cases

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