The study also found evidence that regular physical activity can help mitigate “consequences of serious COVID-19 infection, reducing the risk of hospital admission, intensive care, assisted ventilation, or death,” a press release about the study says.

Researchers reviewed anonymous medical records and wearable-activity-tracker data for health care workers between February and October of 2021 as part of the study. Participants were categorized according to their average physical activity levels. Researchers found that participants who were fully vaccinated and had high weekly levels of physical activity (150 minutes or more per week) were nearly threefold less likely to be admitted to the hospital than participants who were vaccinated but in the low physical activity category (less than 60 minutes per week).

“The findings suggest a possible dose-response where high levels of physical activity were associated with higher vaccine effectiveness,” researchers write in the study. “This substantiates the WHO [World Health Organization] recommendations for regular physical activity—namely, that 150 to 300 minutes of moderate intensity physical activity per week has meaningful health benefits in preventing severe disease, in this context against a communicable viral infection.”

Because the study is an observational one, researchers were unable to establish cause, and results may not be generally applied to other virus variants or types of COVID-19, such as Omicron. Researchers aren’t entirely sure how physical activity strengthens vaccination, but believe it “may be a combination of enhanced antibody levels, improved T cell immunosurveillance, and psychosocial factors.”

“Public health messaging should encourage physical activity as a simple, cost-effective way of enhancing vaccine effectiveness to mitigate the risk of severe COVID-19 illness requiring hospital admission,” researchers add.