Heart health affected the risk of severe COVID-19 infection during the pandemic, says study

On the day the pandemic arrived in America, Tim Plante, M.D., an internal medicine physician at the University of Vermont in Burlington, began noticing a pattern: the patients landing in hospitals with the most severe COVID-19 were not always those he expected. Some had no documented heart disease. Yet something about their cardiovascular fitness—or lack of it—seemed to determine who survived and who didn't.

Now, research led by Plante and published in the Journal of the American Heart Association offers a sobering clarity: between March 2020 and March 2025, COVID-19 killed 1.22 million Americans. Many of those deaths, the study suggests, might have been preventable.

Researchers analyzed nearly 30,000 people using the American Heart Association's Life's Essential 8 metric, a framework that measures eight pillars of cardiovascular health: diet, physical activity, smoking status, sleep, body mass index, blood pressure, cholesterol, and blood sugar. Adults who scored highest on this metric—between 80 and 100 points—had a 46% reduction in their risk of COVID-19 hospitalization or death compared to those with the lowest scores, below 50. The relationship was dose-dependent: for every 14-point increase in the heart health score, the risk of severe infection dropped by 20%.

The findings reveal something physicians have long suspected but rarely quantified. "COVID-19 caused such tremendous impact on the U.S. that it's essential we understand how health components like heart health relate to severity," Plante said. "Our findings suggest that this impact could have been reduced if the general population had better heart health prior to the pandemic."

The implications extend beyond a single virus. Elizabeth C. Oelsner, M.D., an epidemiologist at Columbia University Irving Medical Center, framed it this way: "A viral infection is like a cardiac stress test, except it's not controlled." When COVID-19 swept through America in 2020, it exposed which bodies had been conditioned to withstand extreme physiological stress and which had not. Those with higher scores for physical activity, healthier weight, optimal blood pressure, and better sleep patterns all showed individually lower risks of severe illness.

The study comes from the Collaborative Cohort of Cohorts for COVID-19 Research (C4R), a collaboration of 14 U.S. studies, making it one of the first to leverage Life's Essential 8 metrics to examine how cardiovascular health specifically shaped COVID-19 severity.

The takeaway resonates beyond pandemic preparedness. Sadiya S. Khan, M.D., chair of the American Heart Association's Epidemiology Statistics Committee and a cardiologist at Northwestern University's Feinberg School of Medicine in Chicago, emphasized that healthy lifestyle habits often feel like vague, distant goals. But this research grounds them in immediate, tangible stakes. "Preventing heart disease isn't just about preventing heart disease," Khan noted. "It's about preventing adverse outcomes from respiratory infections."

Khan added an important caveat: vaccination remains critical, particularly for older adults and those with existing heart disease or low heart health scores. Prevention works on multiple levels—the behavioral changes that strengthen the heart, and the vaccines that protect against specific threats.

For millions of Americans navigating the post-pandemic world, the message is clear. The heart health decisions made today may well determine survival in the crises of tomorrow.