The news about the flu seems to keep getting worse: A new study suggests that the risk of heart attack dramatically increases for people who are suffering from influenza.
A study published this week in the New England Journal of Medicine found that heart attacks are six times more likely seven days after a flu diagnosis, compared to a year before or after the flu diagnosis.
"I was a little bit surprised by the strength of the association," chief study author Jeffrey Kwong told Reuters. "It's not every day you see a six-fold increase in the risk during the first seven days of lab-confirmed influenza. We were also surprised the risk dropped off to nothing by day 8 and beyond."
While the medical field has long suspected a connection between influenza and heart attack, it was hard to confirm the association. For the study, researchers used confirmed cases of the flu and analyzed 364 heart attacks from hospital records for Ontario residents spanning 2008 through 2015.
Read more from USA Today:
Fiat Chrysler hourly workers to get $5,500 bonus checks after 2017 profit
Rubbermaid maker Newell Brands to offload half of its plants, customers
Larry Nassar fallout: Michigan State president's resignation comes with lifetime of perks
According to the study, the heart attack rate was 20 admissions per week seven days after a flu diagnosis, compared to only 3.3 heart attack admissions a week in the year before and after a flu diagnosis.
The researchers found that the risk of heart attack increases slightly for those over 65. Sixty nine percent of the 332 people in the study who had a heart attack following a flu diagnosis had not gotten a flu shot, according to the study.
Kwong, a scientist at the Institute for Clinical Evaluative Sciences in Toronto, told Reuters that people should get the flu shot and wash their hands.
Unlike the common cold, flu symptoms hit suddenly — within a matter of hours. Symptoms include: fever, feverish chills, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches and tiredness. Children with the flu could also vomit and have diarrhea, according to the CDC.
Flu has cause inflammation of the heart, brain or muscle tissues; and multiple organ failure.