The risk of a heart attack is 17 times higher in the week after a respiratory infection, according to a study by researchers from the University of Sydney. However, researchers say the absolute risk that any one episode will cause a heart attack is low.

The researchers looked at 578 people who suffered a heart attack and found that 17% had experienced symptoms of respiratory infection within seven days before the heart attack, and 21% within the prior month.

In a second analysis, the researchers focused on upper-respiratory tract infections, such as the common cold, sore throat, hay fever and sinus infections.

“For those participants who reported milder upper-respiratory tract infection symptoms, the risk increase was less, but was still elevated by 13-fold,” study author Lorcan Ruane said in a university news release.