October 30, 2025
Thom Carroll/PhillyVoice
Viral infections, including from COVID-19 and influenza, increase the risk of heart attacks and stroke, a new study finds.
People who haven't gotten COVID-19 or flu shots this fall might be motivated by new research that shows viral infections increase the risk of heart disease and stroke.
People are three times more likely to have a heart attack or stroke in the first 14 weeks after having COVID-19 — and their risk remains heightened for up to a year, the study found. Also, people who had the flu were four times more likely to have a heart attack in the month afterward, and five times more likely to suffer a stroke.
The results were published Wednesday in the Journal of the American Heart Association.
"Preventive measures against viral infections, including vaccination, may play an important role in decreasing the risk of cardiovascular disease," said Kosuke Kawai, the study's lead author and a researcher at UCLA. "Prevention is especially important for adults who already have cardiovascular disease or cardiovascular disease risk factors."
The meta-analysis was based on data from more 155 high-quality, well-designed studies, researchers said.
The also found:
• A 60% higher risk of heart attack and 45% higher risk of stroke in people with HIV
• A 27% higher risk of heart attack and 23% higher risk of stroke in people with hepatitis C
• A 12% higher risk of heart attack and 18% higher risk of stroke in people who had shingles
Inflammation and blood clotting – both involved in the body's attempt to fight viral infections – can impact proper heart function. This may explain the increased risk of heart disease and cardiovascular events after infection with various viruses, the researcher said.
The study "endorses a general idea that we've been thinking about and talking about for the past several years — that infections are generally not benign," Dr. Ziyad Al-Aly, a senior clinical epidemiologist at Washington University in St. Louis, told the New York Times. "It may start as a respiratory virus, but that's really the tip of the iceberg, and it has downstream ramifications in multiple organ systems, specifically in this case in the cardiovascular space."
Al-Aly was not involved in the study.
Anyone 6 months and older can get a COVID vaccine this fall, though the Centers for Disease Control and Prevention recommends that people first have a conversation with a medical provider, including physicians, nurses and pharmacists. The vaccines are covered by private insurers, Medicaid, Medicare and entitlement programs.
The CDC also recommends that most people 6 months and older get an annual flu shot. Like COVID-19 vaccines, they also are covered by private insurers, Medicaid, Medicare and entitlement programs.
