Common infections raise the risk of deadly medical event by FIVE times

Suffering from a Covid, flu or long-term viral infection could raise your risk of a heart attack or stroke, new research suggests.

Scientists at the University of California, Los Angeles, reviewed 155 studies and found that people who suffered from a Covid or flu infection had a five-fold higher risk of these cardiovascular events in the weeks after the infection compared to those who remained healthy.

People who caught the flu were found to have a four-times higher risk of a heart attack and a five-times higher risk of a stroke within a month of their infection compared to people who did not have confirmed flu. 

Meanwhile, those infected with Covid were found to be three times more likely to suffer from a heart attack or stroke in the 14 weeks after infection. For these patients, their risk of cardiovascular problems remained elevated for a year after the infection. 

For patients with HIV, hepatitis C or shingles, researchers found they had an up to 60 percent higher risk of a heart attack and 45 percent higher risk of a stroke overall compared to those who did not have the infections.

Dr Kosuke Kawai, an epidemiologist who led the study, said: ‘It is well recognized that human papillomavirus (HPV), hepatitis B virus and other viruses can cause cancer.

‘However, the link between viral infections and other non-communicable diseases, such as cardiovascular disease, is less well understood.

‘Our study found acute and chronic viral infections are linked to both short- and long-term risks of cardiovascular disease, including strokes and heart attacks.’

Scientists have suspected a link between viral infections and a heart attack or stroke for decades, and this study is the latest to point to a connection.

It’s not clear why the infections raise the risk, but experts believe that activating the immune system triggers widespread inflammation, which, in turn, makes blood more likely to clot, raising the risk of heart-related complications.

Researchers said older adults were at much higher risk after suffering from the infection than younger adults, who generally have a very low risk of heart-related complications.

About 805,000 heart attacks and 795,000 have a stroke every year, according to the CDC. 

Scientists behind the study said their findings suggested everyone should prioritize receiving a Covid and flu vaccine.

CDC monitoring shows Covid levels in wastewater were ‘moderate’ nationwide over the week to September 20, the same as in the previous week.

Flu levels remained ‘minimal’ nationwide, although they are slightly higher in four states: Connecticut, Illinois, North Carolina and Wisconsin.

Flu infections, however, don’t typically peak until December through February, so levels are expected to rise. 

Last year’s flu season was the most severe since 2017 to 2018, with officials recording up to 73million cases, 1.1million hospitalizations and 99,000 deaths.

For the study, published in the Journal of the American Heart Association, scientists analyzed research published between 1997 and 2024.

Among the studies, 137 evaluated the link between heart disease and infection with Covid and/or flu, while 18 studies evaluated the link between the condition and two or more infections.

The researchers also analyzed studies examining long-term viral infections that persist in the body for five years or more, including those involving varicella zoster virus (which causes shingles), hepatitis C, and HIV. 

About 1.2million Americans live with HIV, estimates suggest, while 2.4million have hepatitis C and 1 million have shingles. 

Overall, they found that those infected with HIV had a 60 percent higher risk of a heart attack and a 45 percent higher risk of a stroke overall, compared to those who did not have the infection.

For hepatitis C patients, researchers found they were 27 percent more likely to suffer from a heart attack and 23 percent more likely to suffer from a stroke overall.

And for those who had shingles, they were 12 percent more likely to have a heart attack and 18 percent more likely to have a stroke.

Dr Kawai added: ‘The elevated risks for cardiovascular disease risks are lower for HIV, hepatitis C and herpes zoster than the heightened short-term risk following flu and Covid.

‘However, the risks associated with those three viruses are still clinically relevant, especially because they persist for a long period of time.

‘Moreover, shingles affects about one in three people in their lifetime. Therefore, the elevated risk associated with that virus translates into a larger number of excess cases of cardiovascular disease at the population level.’

The analysis had a number of limitations, including that it was an observational study and could not prove whether the infections raised the risk of a heart attack or stroke o another factor.