Flu Vaccine May Reduce Risk of Heart Attack and Stroke in Hypertensive Individuals

A new study shows cardiovascular outcomes may improve in individuals with hypertension if they receive the influenza (flu) vaccine during the flu season. In the study, the researchers analyzed data from 608,452 people aged 18 years to 100 years who had hypertension and then followed them during nine flu seasons (2007 to 2016), comparing those who had a flu shot and those who did not. Throughout the followup period, the researchers looked at death from any cause, cardiovascular death and death from a heart attack and stroke. They also examined the link between getting the flu shot before the flu season and death risk during the flu season. Age, other medical conditions, medications and socioeconomic status were accounted for. The study revealed an association between vaccination during the flu season and an 18 percent reduction in relative risk of dying from all causes, a 16 percent less relative risk of dying from a cardiovascular event and a 10 percent lower relative risk of dying from a heart attack or stroke.

“During the nine flu seasons we studied, vaccine coverage ranged from 26 percent to 36 percent, meaning that many patients with high blood pressure were not vaccinated,” said lead researcher Daniel Modin, a research associate at the University of Copenhagen, Denmark. “Heart attacks and strokes are caused by the rupture of atherosclerotic plaques in the arteries leading to the heart or the brain. After a rupture, a blood clot forms and cuts off the blood supply. It is thought that the high levels of acute inflammation induced by influenza infection reduce the stability of plaques and make them more likely to rupture.”