According to a new study, presented at the American Heart Association’s Scientific Sessions, vaccination against influenza may reduce the risk of blood clots forming in the veins by 26 percent.

Venous thrombotic embolism (VTE) is a dangerous condition because the blood clot forming in the veins can break loose and travel through the circulatory system to the right side of the heart. The blood clot could easily become dangerous if it manages to travel to the lungs, where it becomes a pulmonary embolism, which can be life threatening or even fatal.

Dr. Joseph Emmerich from the University of Paris Descartes, France and colleagues conducted a case-control study, called FARIVE study, among 1,454 age- and sex-matched patients (average age 52 years) from 11 centers in France. The researchers asked 727 patients hospitalized for a first episode of proximal deep vein thrombosis or pulmonary embolism whether they’d had flu vaccinations in the past year.

The participants also received a standardized questionnaire covering age, educational level, medication history, history of thrombotic disease, use of hormonal therapy, prolonged immobilization. Using these criteria, participants were divided into two groups: patients having secondary or provoked VTE if they had one or more of the risk factors mentioned above and patients with unprovoked episodes of VTE.

Patients who were already diagnosed with the disease were considered ineligible for the study.

The researchers compared patient characteristics of the two groups with those of 727 control subjects, matched for age and sex, who were also hospitalized during the same period, but with no thrombotic disease.

According to the study, the flu shot lowered the likelihood of developing a blood clot by 48 percent among people over the age of 52, it reduced the risk of developing VTE by 50 percent in women 51 years or younger (the risk dropped 59 percent for women in the same category that received contraceptives), the flu shot was associated with a 26 percent reduction in risk for all study participants. The flu shot had a protective effect for other types of VTE as well, such as deep vein thrombosis and pulmonary embolism.

“Our study suggests for the first time that vaccination against influenza may reduce the risk of venous thrombotic embolism (VTE),” lead study author Dr. Joseph Emmerich said in a statement.

Study authors say more research is needed to confirm the relationship between influenza vaccination and VTE. The findings suggest that vaccination against influenza may one day be recommended not only to high-risk patients, but also to patients who have had a prior episode of VTE.

A recent campaign aimed at raising both doctors’ and patients’ awareness about the dangers of blood clots has revealed that each year, a number ranging from 350,000 to 600,000 Americans suffer from a blood clot, of which approximately100,000 die because of it.