Minnesota is experiencing one of the nation’s worst COVID-19 outbreaks, despite a relatively high vaccination rate of 68% for people over age 5.

The apparent contradiction has left many Minnesotans wondering why cases are rising so fast. Here are your questions about Minnesota’s COVID-19 surge, answered.

How bad is it?

Pretty bad. As of Friday, Minnesota had the country’s fourth-highest case rate, at 74 new cases per 100,000 people — surpassed only by Michigan (84 cases per 100,000), New Mexico (79 cases per 100,000) and New Hampshire (77 per 100,000). At one point in the week of Nov. 15, we were the worst in the nation.

Our case counts, hospitalizations and deaths haven’t been this high since this time last year, before the rollout of vaccines. That’s when the state experienced its worst surge, with at least 4,000 new cases daily for much of November — and as many as 9,000 cases in a day — and more than 60 deaths most weekdays in December. (Fewer deaths were typically reported over weekends.)

Right now, we’re seeing roughly 22 deaths per day, based on seven-day averages, and about 4,000 new cases daily.

Hospitals are overwhelmed again as the surge pushes health care workers to the brink, resulting in staffing shortages and long waits for care related to COVID-19 and other injuries and illnesses across the state.

Unvaccinated people are still far more likely to get sick and become hospitalized with COVID-19.

As of early October — the most recent, complete data available from the state — 72,628 fully vaccinated Minnesotans had tested positive for COVID-19, or about 2.2% of vaccinated people. Of that group, 3,177 had been hospitalized, or fewer than 0.01% of vaccinated people.

Minnesota’s current surge still isn’t as severe as the outbreaks in many southern states this summer, however. Louisiana, for example, saw growth rates peak at about 126 new cases per 100,000 residents in August, according to Centers for Disease Control data. Mississippi and Florida were also recording case growth in the triple digits.

Why is it happening?

The short answer: We aren’t sure. A number of factors are to blame, said Dr. Rebecca Wurtz, a University of Minnesota public health researcher.

One-third of Minnesota’s population — or about 1.8 million people — is still unvaccinated.

“We know that Delta will find you if you’re not vaccinated,” Wurtz said.

Vaccination rates are uneven across the state, leaving pockets where large proportions of people are extremely vulnerable to catching and spreading the virus. In 26 counties, at least 50% of the population isn’t vaccinated. In five counties, the rate is under 40%. Low vaccination rates don’t seem to be connected to recent high case rates in some counties, however. For example, both Jackson and Lincoln counties have vaccination rates below 50%, and their seven-day case rates are the lowest in the state, according to CDC data.

• Immunity is waning among people who were vaccinated in early 2020.

Many people are surprised that Minnesota’s COVID-19 case rates are rising, given the state’s relatively high vaccination rate, Wurtz said — nearly 70% of people over the age of 5.

Immunity seems to decline about six months after receiving the second shot of Pfizer or Moderna, or two months after receiving the Johnson & Johnson, which explains some of the surge, she said.

Plus, people at highest risk for severe illness — those over 65 or with underlying conditions — were vaccinated earliest, meaning their immunity started waning earliest as well.

“We knew that immunity would wane, but I don’t think we knew it would wane like clockwork — right on schedule,” Wurtz said. “It’s just (happening) absolutely six months after people are vaccinated.”

About 2.2 million Minnesotans got two Pfizer or Moderna shots before May 20, and 293,000 got the one-shot Johnson & Johnson by Sept. 20.

About 715,000 people have gotten boosters, according to the state, leaving roughly 30% of the state’s population vulnerable to getting sick at this point in the year, despite being vaccinated.

• The highly contagious Delta variant is still circulating widely.

The Delta variant may be two times more contagious than earlier variants, studies suggest, and could be more likely to cause severe illness. It now accounts for more than 99% of cases in the United States, according to the CDC.

Vaccines seem to offer less protection against the Delta variant, according to a recent study of nearly 800,000 veterans in the U.S., although they’re still effective in preventing infection and reducing the likelihood of hospitalization or death.

Plus, the vaccines don’t seem to prevent people from transmitting the virus in breakthrough cases like experts had hoped it would, Wurtz said. Fully vaccinated people aren’t as contagious as unvaccinated people, but they’re still “pretty infectious, especially with this Delta variant,” she said.

• We’re spending more time inside.

Some experts have suggested cold weather is to blame, as the virus is more likely to spread indoors. Wurtz isn’t convinced that’s a major factor, however, since it doesn’t explain patterns across the nation.

“States that were on fire this summer — Florida, Texas, the south — are not on fire anymore, and nobody knows why,” Wurtz said. “People there are inside more now than they were in the summer, and they’re not experiencing what we are.”

• Many of us are letting our guard down.

Unlike earlier this year, social distancing and masking are optional in many places, indoor dining restrictions are no more, and big events like concerts, sporting events and weddings are back — although some have implemented vaccination or testing policies.

“Unfortunately, it’s clear that many people are done with the pandemic, even though the pandemic is not done with them,” Michael Osterholm, a University of Minnesota epidemiologist, told MPR News.

• What precautions should I take?

Mask up, get vaccinated if you haven’t already, and get the booster six months after your second Pfizer or Moderna shot, or two months after your Johnson & Johnson jab. Boosters are available to everyone in Minnesota — call your doctor to see if they’re offering them, or find one here.

It’s also time to pump the brakes on riskier outings, including indoor events and anything with large crowds, Wurtz said. She said she personally doesn’t feel comfortable eating inside a restaurant, going to a concert or a movie right now, but she feels fine about going to the grocery store or holiday shopping with a mask on.

Wurtz said she also feels comfortable having maskless Thanksgiving gatherings with fully vaccinated people who have no symptoms.

Minnesotans should also consider limiting potential exposures ahead of holiday gatherings, especially if they plan on getting together with people susceptible to serious illness or death, Wurtz said. She expects this wave to last until at least mid-January.

“We’re in this weird threshold phase that may last through January,” she said. “We need to back off a little bit again, pending the next six weeks or so, and be more cautious about our social circles and the events that we think are worth risking exposure.”

Rilyn Eischens is a data reporter with the Minnesota Reformer.

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