It’s cold and flu season, a source of stress and anxiety for some people—like senior or immunocompromised folks. But for many others, catching the flu is an unpleasant reality but nothing to worry about.
A sweeping new analysis published in the Journal of the American Heart Association, reveals that it is beyond time to rethink everyday viral infections like the flu. Researchers found that some acute and chronic viral infections—including flu, COVID-19, shingles, and others—can significantly increase the risk of cardiovascular disease, including heart attacks and strokes.1
In other words, even a virus that feels “mild” in the moment can leave a deeper imprint on the body than most of us realize. Protecting your immune system isn’t just about avoiding a few days in bed—it’s about safeguarding your long-term heart health, too. Let’s review the history and some ways to protect yourself.
A History of Clues: What Doctors Have Long Suspected
The idea that viruses can strain the heart isn’t new. As far back as the 1930s, researchers observed a connection between influenza infection and cardiovascular complications. A 1932 report titled, “Excess Mortality from Causes other than Influenza and Pneumonia during Influenza Epidemics” described how flu outbreaks often coincided with a spike in heart-related deaths.2
Over time, scientists have learned that viral infections can trigger widespread inflammation, increase blood clotting, and even damage blood vessel linings—all of which can stress the cardiovascular system. Still, the link between respiratory infections and heart disease has often been overlooked outside of medical circles.
In fact, an analysis published earlier in 2025 offers another layer of historical perspective. Researchers examined post-pandemic cardiac mortality rates in the United States and found that deaths from heart disease remained elevated well after the peak of the COVID-19 pandemic, particularly among middle-aged adults.3 The findings suggest that viral outbreaks can have lingering effects on cardiovascular health long after infection rates decline.
The takeaway is clear: each wave of widespread viral infection leaves behind more than temporary respiratory illness—it can alter long-term patterns of cardiovascular risk across entire populations.
Today’s scientists are connecting those dots more precisely than ever before, uncovering how inflammation, immune response, and vascular injury converge to make viral infections a significant, and often underestimated, threat to heart health.
The 2025 Meta-Analysis: 155 Studies, One Clear Message
The new study, published just last week, is one of the most comprehensive reviews ever conducted on the connection between viral infections and cardiovascular disease.
Researchers followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines—the gold standard for scientific transparency and consistency. In other words, the process was meticulous, designed to ensure objectivity and reproducibility.
Of the 52,336 studies initially screened, 155 met the strict inclusion criteria. These studies covered both acute (short-term) infections—like influenza and COVID-19—and chronic infections such as HIV, hepatitis C, and shingles (herpes zoster).
The research spanned continents—North America (67 studies), Europe (46), and East Asia (32)—and most (137) focused on a single viral infection. Importantly, 71% of the included studies adjusted for key confounding factors such as age, sex, and traditional cardiovascular risk factors, meaning the associations observed weren’t just coincidence or lifestyle-related.
And the results were striking:
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Influenza infection was linked to a fourfold increase in heart attack risk and a fivefold increase in stroke risk within the first month of illness.
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COVID-19 infection was associated with a 74% higher risk of coronary heart disease and a 69% higher risk of stroke compared with people who never had COVID.
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Hepatitis C, HIV, and herpes zoster (shingles) were all tied to long-term elevations in cardiovascular risk.
Taken together, these findings confirm that viruses don’t just affect the lungs—they can also disrupt the body’s delicate cardiovascular balance. Whether an infection is acute or chronic, it can drive inflammation that damages blood vessels, promotes clotting, and accelerates the kind of arterial changes that lead to heart disease.
For researchers, the message is clear. For the rest of us, it’s a powerful reminder that supporting immune and cardiovascular health go hand in hand.
Prevention: Protect Your Health, Protect Your Heart
The good news is that the same steps that help prevent flu, COVID, and other viral infections can also help safeguard your heart.
Fortunately, the same simple healthy habits that help prevent colds, flu, and other respiratory infections can also help protect your heart. According to the Centers for Disease Control and Prevention (CDC), reducing your risk of viral illness is one of the most effective ways to lower the chance of heart complications that can follow infection.4
Avoid close contact: When possible, avoid being near people who are sick. If you’re the one who’s not feeling well, give others space until you’re on the mend. Physical distance helps slow the spread of respiratory viruses—especially in households, offices, and classrooms where germs can easily circulate.
Stay home when you’re sick: Rest and recovery are good for both your immune system and your heart. Stay home from work, school, or errands until you’ve been fever-free for at least 24 hours (without fever-reducing medication) and your symptoms are improving. Once you’re feeling better, take extra care for another day or two to protect those around you.
Cover coughs and sneezes: Use a tissue or your elbow—not your hands—to cover your mouth and nose when you cough or sneeze. This simple step helps prevent droplets from spreading to others.
Keep hands clean: Regular handwashing remains one of the easiest and most effective ways to stop viruses from spreading. Wash with soap and water for at least 20 seconds, or use a hand sanitizer containing at least 60% alcohol when soap isn’t available. Avoid touching your eyes, nose, or mouth to reduce the chance of germs entering your body.
Practice good hygiene and healthy habits: Clean high-touch surfaces like doorknobs, phones, and countertops often. Support your immune system by getting enough sleep, staying active, managing stress, and eating nourishing foods. A resilient body is better equipped to handle infections—and that means less strain on your heart.
Improving indoor air quality: Clean, well-ventilated air is essential to limiting airborne virus exposure—especially in busy indoor environments where germs can linger. Opening windows when weather allows, upgrading HVAC filters, and using a high-efficiency Austin Air Purifier can all help reduce viral particles in the air, while also helping to lower your body burden and supporting overall immune strength.
Austin Air Purifiers use medical-grade HEPA and a significant amount of activated carbon which captures viruses, bacteria, and fine airborne contaminants that can strain the immune system and cardiovascular health alike.
In fact, if you’re a parent or care-giver for a school aged child, an Austin Air Purifier could even make a thoughtful and potentially life-changing classroom gift. (Or perhaps a filter replacement for schools that purchased Austin Air Purifiers during the height of the pandemic.) A study conducted in Finland showed that air purifiers reduced the spread of illness in daycares, which has impacts today and before the next pandemic.5 Consider teaming up with other families this holiday season to provide an Austin Air purifier for your child’s teacher—a gift that supports cleaner air and stronger hearts all year long.
The Bottom Line
The flu might not seem so bad—just a week of sniffles and fatigue—but for someone with hidden heart vulnerabilities, even a “common” virus can be the spark that reveals a deeper issue.
Science continues to show how connected our body systems are: what affects the lungs often affects the heart. And that makes prevention—through healthy habits and clean indoor air—more important than ever.
REFERENCES
1 Kawai K, Muhere CF, Lemos EV, and Francis JM. (2025 October 29). Viral Infections and Risk of Cardiovascular Disease: Systematic Review and Meta‐Analysis. Journal of the American Heart Association. 14(21):e042670. doi: 10.1161/jaha.125.042670.
2 Collins, SD. (1932 November 11). Excess Mortality from Causes Other than Influenza and Pneumonia during Influenza Epidemics. Public Health Reports (1896-1970). 47(46):2159–2179. doi: 10.2307/4580606.
3 Wasfy JH, Lin Y, Price M, et al. (May 2025). Postpandemic Cardiac Mortality Rates. JAMA Netw Open. 8(5):e2512919. doi:10.1001/jamanetworkopen.2025.12919.
4 Healthy Habits to Prevent Flu. (2024 August 20). US Centers for Disease Control. https://www.cdc.gov/flu/prevention/actions-prevent-flu.html.
5 E3 Pandemic Response and Enterprise Solutions. (2024 September 11). Air purification reduces children’s morbidity in the daycare. E3 Pandemic Response. https://www.pandemicresponse.fi/post/air-purification-reduces-childrens-morbidity-in-the-daycare.
