Common viral infections such as flu, HIV, hepatitis C and shingles can increase the risk of stroke and heart disease, according to a large review of 155 studies.
The meta-analysis found that people who caught flu were up to six times more likely to have a heart attack in the month after infection, while those who had COVID-19 were nearly twice as likely to develop heart disease or stroke compared with those who had not been infected.
Researchers from the David Geffen School of Medicine at the University of California, Los Angeles, reviewed decades of data and found that viral infections can raise cardiovascular disease risk both immediately after infection and over the longer term.
The analysis showed that influenza and COVID-19 infections were linked to a higher risk of acute cardiovascular events such as heart attacks.
Chronic viral infections including HIV, hepatitis C and shingles were associated with a long-term increase in coronary heart disease and stroke risk.
The researchers also noted that other viruses – including cytomegalovirus, herpes simplex, hepatitis A, human papillomavirus (HPV), respiratory syncytial virus (RSV), dengue and chikungunya – have been linked to an increased cardiovascular risk, though more research is needed to confirm these associations.
“One way to prevent this is really vaccination,” said lead study author Dr Kosuke Kawai, adjunct professor at the David Geffen School of Medicine.
“Often, we get vaccinated to reduce the risk of influenza or other illness, but I think vaccines can provide additional benefit in terms of potentially protecting against cardiovascular disease.”
Dr Scott Roberts, associate medical director for infection prevention at the Yale School of Medicine, explained that viruses can affect the heart in two ways.
They may act indirectly by triggering an overactive immune response, causing inflammation, stress and blood clotting that harm the heart, or directly by attacking heart tissue.
Most respiratory viruses – including COVID-19, flu and RSV – act through the indirect pathway, Roberts said, while enterovirus strains related to those causing hand, foot and mouth disease can directly infect the heart muscle.
“Generally, the more severe the viral illness, the greater the risk of cardiovascular complications,” Roberts said.
He added that such infections can also worsen existing heart problems such as heart failure.
Kawai said it is difficult to quantify exactly how likely someone with a viral infection is to develop cardiovascular disease, so everyone should take preventive measures.
“It’s not just the patients who have underlying increased risk for cardiovascular disease that might be at greater risk, but those who are younger adults, or people who might not necessarily have some of the risk factors for cardiovascular disease, are also at increased risk,” he said.
The researchers said preventive steps such as vaccination and timely antiviral treatment could help reduce the global burden of cardiovascular disease, which remains the world’s leading cause of death.
“Vaccines for many of these viruses exist and generally lessen the risk of cardiovascular events after infection, since the severe infection is more likely to be mild in a vaccinated individual,” Roberts said.
In people with healthy immune systems, vaccines are protective because they contain either an inactivated virus or specific parts of the pathogen.
These cannot trigger an overactive immune response or directly damage heart tissue, Kawai explained.
Anyone worried about heart problems following a viral infection should speak with their doctor, Roberts advised.
