Minnesota has identified its first COVID-19 cases involving the BA.4 and BA.5 coronavirus subvariants that have shown the ability in other nations to spread even in highly immunized populations.
Genomic sequencing of a sampling of positive coronavirus infections found BA.4 in four cases and BA.5 in one case — with four involving residents outside the Twin Cities, according to the latest data from the Minnesota Department of Health. Identified specimens involving a BA.2.12.1 subvariant, which is causing high COVID-19 levels in the Northeast now, have increased over the past week from 47 to 131.
Whether these variants will accelerate COVID-19 cases in Minnesota is unclear. While earlier delta and omicron variants produced record infections this winter, a beta variant did not produce much viral spread locally last spring after it was identified in Brazil.
One reason for concern is that the two new subvariants spread rapidly in South Africa despite recent COVID-19 waves that should have left people there with short-term immunity after infection, said Dr. Gregory Poland, head of Mayo Clinic's COVID-19 vaccine research group.
"BA.4 and BA.5 ... very efficiently escape that immunity," Poland said in a podcast released this week. "So they are having a major surge with BA.4 and BA.5 driving up cases, hospitalizations and deaths."
Pandemic activity already is increasing in Minnesota, but growth in infections continues to outpace severe illness and hospitalizations. The state on Wednesday reported another 2,120 coronavirus infections.
Nearly 1.5 million Minnesotans have tested positive for COVID-19, including 68,742 people who have been infected more than once. The total excludes positive at-home test results that aren't reported to public health authorities. Minnesota's actual infection total could be above 3.3 million, including unreported and asymptomatic cases, according to federal estimates.
State health officials are hopeful that high immunity levels from recent vaccinations and infections are at least reducing severe COVID-19 illnesses. Hospitalizations in Minnesota of patients with COVID-19 have increased from 183 on April 10 to 440 Tuesday. However, hospitals are reporting a higher proportion of patients admitted for other purposes whose COVID-19 positive tests only turn up due to routine screening.
COVID-19 hospitalizations requiring intensive care have increased from a low of 20 on April 25 to 31 Tuesday. The latest ICU total only makes up 7% of the current COVID-19 hospitalizations, though. During earlier pandemic waves, ICU patients accounted for up to 30% of the hospitalizations.
Allina Health reported that COVID-19 positivity among symptomatic patients in the hospitals increased from about 3% in the week ending April 10 to about 16% in the week ending May 8. Among hospitalized patients with no COVID-19 symptoms, the comparable test positivity rate has increased from nearly 2% to almost 4%.
COVID-19 patients placed on ventilators because of severe lung problems declined from 48 in early February to only one earlier this month.
The state on Wednesday reported six COVID-19 deaths in seniors.
The age trend of COVID-19 mortality has shifted back toward seniors, who account for 82% of Minnesota's 12,575 deaths in the pandemic. Only 72% of deaths involved seniors since last June, when the delta variant took a larger toll among younger, unvaccinated adults. However, since March, seniors have once again made up more than 80% of Minnesota's COVID-19 deaths.