The flu can increase the risk of stroke, tears of artery to the neck

WEDNESDAY, January 30, 2019 (HealthDay News) – The flu can make you extremely sick, but it could also cause a stroke or rupture of the arteries in your neck, according to two new studies.

The researchers have issued an urgent reminder that the influenza vaccine will not only protect you from infection, but may also reduce the risk of serious complications.

Researchers in the first study found that influenza can increase your chances of getting a stroke by almost 40% – and that the extra risk lasts for a full year.

"The risk is highest during the 15 days of flu and begins to decline over time," said lead researcher Amelia Boehme. She is Assistant Professor of Epidemiology at the College of Physicians and Surgeons Vagelos of Columbia University in New York.

For the study, Boehme and colleagues identified nearly 31,000 patients in a database in New York State, aged 72 on average, with a stroke in 2014. As a group, they had tend to have more severe cases of influenza, since they have all been seen in an emergency room or admitted to the hospital.

The Boehme team expects to find differences in risk of stroke between men and women, urban and rural people and blacks and whites. Instead, the researchers found that the risk of stroke after fighting the flu was similar.

Other studies have shown that the risk of stroke increases after any major infection. It could be that in people already at risk of stroke, the flu triggers one, said Boehme. But this study has not shown that the flu causes an increased risk of stroke.

Still, patients need to be closely monitored after getting the flu, said Dr. Salman Azhar, director of stroke care at Lenox Hill Hospital in New York.

"What's interesting here is that the flu not only increases the risk of stroke, but also that it's a prolonged risk, which lasts several months, "he said. "People need to get vaccinated."

Azhar suspects that inflammation badociated with an infection such as the flu makes the body vulnerable to strokes and heart attacks.

"The flu puts a strain on your immune system and you have a lot of inflammation, and it persists," he said. "This is not an isolated risk, the risk has been around for several months."

In the second study, another group of researchers at Columbia University found that in the month following an influenza, patients were more likely to tear their neck arteries.

"Previous studies have shown that non-traumatic cervical artery tear is one of the leading causes of stroke in patients 15 to 45 years of age," said lead researcher Madeleine Hunter, a medical student. "However, it is not known how the dissections of the arteries of the neck are without major trauma."

Using the same data as in the first study, the Hunter team examined nearly 3,900 cases of cervical artery tear in men and women, averaging 52 years old.

They also identified more than 1,700 cases of influenza and found 113 cases of influenza patients in the three years preceding a torn neck artery. The flu was most likely to occur in the 30 days before the tear.

"The fact that our study has highlighted an badociation between influenza and cervical artery tear and that it fades over time suggests that the flu could be a trigger," he said. Hunter said.

Dr. Marc Siegel, a professor of medicine at the Faculty of Medicine at New York University in New York, reviewed the results.

"The flu causes a hyperimmune response and can increase blood clotting and wear," he said. But the flu problem is not just about the flu itself, Siegel said. On the contrary, it opens the door to other life-threatening diseases.

One of the underestimated aspects of the flu vaccine is that, if you catch the flu, it will probably be a less serious case, Siegel said. "I would expect complications like these, which are extreme, to be less common with influenza vaccines."

The results will be presented from February 6 to 8 at the annual meeting of the American Stroke Association in Honolulu. Research presented at meetings is generally considered preliminary until it is published in a peer-reviewed journal.

More information

To learn more about influenza, heart disease and stroke, visit the US Center for Disease Control and Prevention.