The benefits of vaccination against respiratory syncytial virus (RSV for short) may go far beyond protection against a serious respiratory illness.
A large new study involving more than 17,000 adults found that those who had a bout of RSV also faced a significantly greater risk of heart attack, stroke, and other life-threatening cardiovascular complications than adults who didn’t get an RSV infection — especially within the first 30 days after getting sick.
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“The results suggest that RSV vaccination might help prevent cardiovascular events,” says the lead study author, Anders Hviid, a professor and the head of the epidemiology research department at Statens Serum Institut in Copenhagen, Denmark.
The link between RSV and serious heart problems was strongest for people hospitalized with RSV, adults 85 and older, and those with preexisting heart disease. “If you are elderly or have preexisting conditions that make you vulnerable to infections, you should really consider getting an RSV shot,” Hviid says.
What Is RSV and How Does It Harm the Heart?
Respiratory syncytial virus is a common germ that can infect the nose, throat, lungs, and airways. For most healthy children and adults, RSV infection causes mild, cold-like symptoms. But RSV can be serious and even life-threatening to infants, adults over 65, and people with weakened immune systems or preexisting lung or heart disease.
The new research aligns with growing evidence connecting RSV infection to cardiovascular problems.
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“We know that RSV is a respiratory virus that promotes inflammation in many organs other than the lungs,” says Juanita Mora, MD, a medical spokesperson for the American Lung Association and the CEO of Chicago Allergy Center.
“Just like COVID-19, now we are finding out that RSV infection can put people at risk for cardiovascular events as well, such as heart attacks, arrhythmias, and strokes, along with thromboembolism,” or blood clots, says Dr. Mora, who was not involved in the study.
Study Looked at Adults 45 and Older
To get a better grasp on whether RSV might heighten heart risks, Hviid and his team turned to Danish health registries to identify nearly 9,000 adults age 45 and older who had a confirmed RSV diagnosis. They compared that group’s health outcomes with records from a matched group of similar adults who hadn’t gotten RSV.
Information on whether participants had received an RSV vaccine was not included because vaccination was rare during the study period between 2019 and 2024, says Hviid.
The scientists calculated that among the RSV group, there were nearly five additional heart crisis events for every 100 adults in the year following infection.
Compared with matched controls without infection, the risk of a cardiac event after RSV infection was higher for adults who were:
- Hospitalized with RSV (6.6 percent higher)
- Ages 85 to 94 (nearly 8 percent higher)
- Already had heart disease (12 percent higher) or diabetes (7.5 percent higher)
The risk of a cardiac event was highest during the first 30 days after diagnosis, says Hviid.
“This makes sense, since that is when your body is most under strain,” he says.
Younger adults who contracted RSV faced a small degree of elevated heart risk — about a 1 percent higher risk of events like heart attack or stroke for those ages 45 to 54.
“If you are 45, otherwise healthy, and have a mild RSV infection, I would not worry,” says Hviid.
RSV and Flu Both Put the Heart at Risk
To find out whether it was RSV in particular, or the stress of an acute infection, that was causing the heightened heart risks, the researchers also compared the RSV participants with an equal number of adults who got the flu.
They found no significant differences in heart crisis risks between people who got the flu and those who got RSV. This suggests that the specific type of respiratory infection may not be as significant as its severity.
“This makes sense biologically,” says Jeffrey Klausner, MPH, MD, a professor of medicine and public health at the USC Keck School of Medicine in Los Angeles, who was not involved with the study. “The mechanisms that cause heart attacks or strokes related to flu are probably similar in terms of RSV, such as trouble breathing and poor oxygen intake.”
He explains that in the process of fighting infection, the body activates its immune system, causing fever, increasing the heart rate, and generally, putting more demands on the heart.
“The immune system activation causes collateral damage, increasing inflammation in the blood vessel walls and a thickening of the blood. Plaques may then rupture in the arteries and cause blood clots, directly causing a heart attack or stroke,” says Dr. Klausner.
What Are the Most Serious Symptoms of RSV Infection?
These heart-related consequences underscore the importance of getting the RSV vaccine if you’re among those considered vulnerable to serious illness.
Although symptoms are often mild (resembling a common cold and passing with little problem), adults with weaker immune systems who get RSV can experience:
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- Shortness of breath
- Severe wheezing
- Disorientation
- High fever
- Pneumonia
- Worsening of chronic conditions such as asthma and COPD
Each year, an estimated 110,000 to 180,000 adults ages 50 and older in the United States are hospitalized because of RSV, according to the Centers for Disease Control and Prevention (CDC). The health agency estimates that vaccination reduces the risk of hospitalization for RSV by 75 percent among older adults.
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Which Adults Should Get an RSV Shot?
The CDC recommends the RSV vaccine for all adults ages 75 and older and for adults ages 50 to 74 who are at increased risk of severe RSV illness.
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“Sadly, I think many adults are woefully unaware of the adult RSV vaccine. Many of my friends have never heard of it nor the pneumonia vaccine,” says Klausner. “We need to do a lot more in terms of general public education about the benefits of these respiratory vaccines.”
Some adults may not think vaccination is for them because RSV is often regarded as a childhood illness (it infects most kids by age 2).
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Also, these vaccines are relatively new. Since May of 2023, the U.S. Food and Drug Administration has approved three adult RSV vaccines:
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- Arexvy (from GSK)
- Abrysvo (Pfizer)
- mResvia (Moderna)
One More Reason to Get Vaccinated
The authors acknowledged that as an observational study relying on preexisting data, the research shows a link, but doesn’t outright prove that RSV raises the risk of heart attack, stroke, and other cardiovascular events.
The study also draws on a population only from Denmark, so outcomes may be different in groups of people elsewhere around the globe.
In the near future, Hviid hopes to see the findings backed up by randomized clinical trials of RSV infection in adults with long-term follow-up.
Still, the latest results are compelling enough to give people one more reason to get their RSV shot.
“This only strengthens our recommendation for RSV vaccination in adults to protect them from short term and long-term complications,” says Mora.
