HealthPartners, national study back safety of two-dose COVID-19 vaccines

A review of 6.2 million vaccine recipients in Minnesota and seven other U.S. regions found no significantly elevated rates of conditions such as stroke or heart attack immediately following COVID-19 vaccination.

Bloomington-based HealthPartners contributed to the national study, which looked for elevated rates of 23 potential side effects, including conditions such as Guillain-Barré syndrome or Bell's palsy that are associated with other vaccines, and problems such as myocarditis that have been found in rare COVID-19 vaccine recipients.

The researchers looked for elevated rates in the first three weeks after people received Pfizer or Moderna COVID-19 vaccines — a time frame when side effects from other vaccines traditionally emerge — but found none in comparison to rates of those conditions they suffered in the three weeks after that.

"Vaccines are our best hope for returning to more normal lives," said Dr. Elyse Kharbanda, a senior investigator with the HealthPartners Institute and a co-author of the study, which was published Friday by the Journal of the American Medical Association. "They help prevent COVID-19 and we can feel even more confident that they're safe."

The findings address a key concern that has kept people from seeking a vaccine and held Minnesota's first-dose COVID-19 vaccination rate at 70.8%. Gov. Tim Walz has offered a series of incentives for new recipients — starting with free fishing licenses and event tickets earlier this summer and later offering $100 cash bonuses.

State health officials hope that vaccination progress will blunt the pandemic wave that is being fueled by a highly infectious delta variant of the coronavirus that causes COVID-19. The Minnesota Department of Health on Friday reported 2,138 infections and 5 COVID-19 deaths, raising the state's totals to 655,418 infections and 7,844 fatalities.

COVID-19 hospitalizations in Minnesota rose to 626 on Thursday — up from 90 on July 14.

Hospitalizations of children with COVID-19 in 14 states, including Minnesota, have increased nearly fivefold from June to mid-August when the delta variant surged, according to a report published Friday by the U.S. Centers for Disease Control and Prevention.

Epidemiologists from the Minnesota Department of Health co-authored the report, which found no increase in disease severity along with the increase in hospitalizations. They reported a hospitalization rate for unvaccinated children age 12 to 17 that was 10 times higher than the rate for vaccinated children.

Minnesota has had an influential role in COVID-19 vaccine monitoring, mostly with the two-dose Pfizer and Moderna vaccines that were approved in December by the U.S. Food and Drug Administration under temporary emergency use authorizations. The Pfizer vaccine has since received full FDA approval. Studies have been limited of the single-dose Johnson & Johnson vaccine, which was approved later.

Duluth-based St. Luke's is part of a national group monitoring vaccine effectiveness in hospital workers and first-responders who were among the first recipients. Rochester-based Mayo Clinic published an analysis of its patients last month, showing a decline in the effectiveness of the two-dose vaccines in preventing infections — perhaps because of the delta variant — but a strong level of protection against severe COVID-19 illnesses and hospitalizations.

The HealthPartners study was led by Kaiser Permanente researchers in California and was the first detailed public report from a group called the Vaccine Safety Datalink.

Marshfield Clinic in northwest Wisconsin is part of the group, which has been providing weekly updates on vaccine safety to the federal Advisory Committee on Immunization Practices and plans to continue monitoring vaccinated patients for two years.

The study was designed for speed by comparing outcomes in the first three weeks after vaccination, when side effects would be most likely, with the next three weeks after that. Kharbanda said it also offers benefits over studies that compare vaccinated and unvaccinated individuals over time.

People who were sicker, older, and at greater risk of viral exposure received the first doses when they became available, making it harder to compare them with the rest of the population, she noted.

Kharbanda said the study was reassuring because it was large enough to measurably detect vaccine-related side effects. However, the statistical confidence intervals were fairly broad for the findings involving some of the 23 conditions, meaning more research is needed to ensure that vaccination isn't posing a risk.

The analysis found 34 cases of myocarditis and pericarditis — inflammation in and around the heart — in vaccine recipients. All were younger than 40 and more than half were younger than 25. A secondary review concluded that there was an elevated risk of this condition in the first seven days after receiving vaccine. While 82% of the patients with this condition needed hospital admissions, all recovered.

Other studies found that the rate of myocarditis following coronavirus infection is higher than after vaccination.

Jeremy Olson • 612-673-7744