A study led by IiSGM concludes that flu vaccination reduces severe heart attacks and pulmonary blood clots in critically ill cardiac patients
Researchers from the Clinical Microbiology and Infectious Diseases and Natural History of Heart Disease groups participate
Researchers from the Instituto de Investigación Sanitaria Gregorio Marañón (IiSGM) are leading a new multicentre scientific study conducted in Spain which suggests that the flu vaccine acts preventively for the heart, reducing the occurrence of severe heart attacks, pulmonary embolisms and critical clinical situations.
The study, published in the scientific journal International Journal of Infectious Diseases, prospectively analysed almost 400 patients admitted to the Cardiac Intensive Care units of five major Spanish hospitals over three consecutive flu seasons.
Researchers from the Microbiología Clínica y Enfermedades Infecciosas and Historia Natural de la Enfermedad Cardíaca groups of the IiSGM found that patients who had been vaccinated before the flu season had a significantly lower probability of being admitted to the ICU due to an acute myocardial infarction with ST-segment elevation—the most severe type of heart attack—compared with unvaccinated patients: 28.2% versus 40.8%.
They also discovered that being vaccinated reduces the risk of suffering a pulmonary embolism, with rates of 0.8% in the vaccinated group compared with 4.6% in the unvaccinated group. In general, patients who had not received the vaccine suffered considerably more serious medical conditions during their hospital stay.
The key lies in the amount of antibodies
Beyond analysing whether the patient was vaccinated or not, the research team accurately measured the actual level of immune protection in the patients’ blood. The analysis, in which the Centro Nacional de Gripe de Valladolid closely collaborated, showed that the body’s protection was much stronger against type A flu viruses, especially the H3N2 subtype, than against type B viruses.
The study’s most novel finding is that the amount of immune defences matters. It was observed that having low levels of antibodies in the blood is directly associated with a higher occurrence of severe heart attacks and pulmonary embolisms, as well as cardiogenic shock or cardiorespiratory arrest. This suggests that the vaccine helps to keep generalised inflammation under better control and stabilise the arteries, preventing the formation of the clots that cause heart attacks.
"Flu can be the final push that triggers a serious cardiovascular event in vulnerable people, even if the infection goes almost unnoticed. Our data show that vaccination not only prevents a respiratory illness, but also directly modulates the risk of suffering a cardiac catastrophe”, explains Alicia Galar, a doctor in the Servicio de Microbiología Clínica y Enfermedades Infecciosas and a researcher in the Microbiología Clínica y Enfermedades Infecciosas group of the IiSGM.
Until now, it was known that having the flu increases the risk of suffering a heart attack sixfold in the days following the infection. With this new evidence, the researchers insist that the flu vaccine should be considered a priority and mandatory secondary prevention strategy for any patient with a history of heart disease, comparable to the daily medication they take to control their condition.
The study was led by specialists from the servicios de Microbiología Clínica y Enfermedades Infecciosas and de Cardiología del Hospital General Universitario Gregorio Marañón, linked respectively to the Microbiología Clínica y Enfermedades Infecciosas and Historia Natural de la Enfermedad Cardíaca groups of the IiSGM.
Researchers and clinical professionals from the Hospital Clínico Universitario de Valladolid, the Hospital Universitario La Paz, the Hospital Universitario Doce de Octubre, the Hospital Universitario Puerta de Hierro and the Complejo Hospitalario Universitario de Santiago de Compostela collaborated on the research. In addition, the work was carried out as part of a collaboration between several groups from the Centros de Investigación Biomédica en Red, specifically the CIBER de Enfermedades Respiratorias, the CIBER de Enfermedades Cardiovasculares and the CIBER de Enfermedades Infecciosas.
