Influenza vaccination may significantly reduce the risk of influenza-related heart attacks and strokes, even in people who become infected after vaccination, according to a recently published study. euro monitoring.
Getting the flu increases your short-term risk of cardiovascular disease, but existing evidence shows that vaccines reduce the risk of heart attack and stroke by preventing infection in the first place. The study by Croci and colleagues looked at 1,221 Danish adults aged 40 and older to determine how much their risk increases after infection, and whether vaccines can reduce this additional risk even if they do become infected.
“If confirmed by additional studies in other settings, this would strengthen the case for prioritizing influenza vaccination for people at risk of heart disease and stroke and refine recommendations across Europe.” Croci et al.
Hospitalizations due to heart attacks and strokes after influenza infection increase rapidly
The study used Danish health registry data from 2014 to 2025 and included individuals aged 40 and older who were hospitalized for the first time with a heart attack or stroke within about a year after infection with the influenza virus. This included all laboratory-confirmed influenza virus infections that occurred during nine consecutive influenza seasons with an observation period of 365 days before and after a positive influenza test. Records of tests, hospitalizations, vaccinations and mortality were matched through Denmark’s unique personal identifiers.
The study subjects consisted of 660 men and 561 women over the age of 40, with a median age of 75. Most patients (65%) were admitted with a stroke, and 35% had a heart attack. Of the 1,231 influenza virus infections confirmed by PCR testing, about half occurred after patients had been vaccinated. The researchers used conditional Poisson regression to estimate incidence rate ratios (IRRS) and 95% confidence intervals using a self-controlled case series design. A self-controlled case series design is a research design that compares the timing of events within the same person, thereby controlling for other individual factors such as comorbidities, genetic predisposition, and socioeconomic status. The 2-week pre-exposure period before testing was excluded to minimize reverse causality, i.e., where cardiovascular symptoms may have prompted testing.
The risk of a first hospitalization for a heart attack or stroke was found to be significantly higher in the first week after a positive flu test than at any other time before or after. It increased threefold for stroke and fivefold for heart attack.
This increased risk was cut in half among people who were infected but received the flu vaccine that flu season.
The study did not take into account differences in effectiveness between influenza vaccines, which may depend on how well the vaccine formulation matches the virus strains circulating that season. We also could not assess whether timing of vaccination or gender affected outcomes. Additionally, results may not be directly applicable to populations or settings with different influenza epidemiology, health care systems, and vaccination strategies.
Protective efficacy may influence vaccination strategies
According to Croci et al.This highlights the dual protection provided by vaccination against both infectious diseases and their cardiovascular complications, which can have important implications for public health.”
Incorporating the vaccine’s additional protection against these conditions into economic and burden analyzes may also help make a stronger case for the economic case for influenza vaccination programs.
sauce:
European Center for Disease Prevention and Control (ECDC)
Reference magazines:
The flu vaccine may protect against heart attacks and strokes even in infected people. euro monitoring. DOI: 10.2807/1560-7917.ES.2026.31.13.2500706
