Flu Vaccine May Protect Against Heart Attack, Cardiovascular Events


Study authors recommend that healthcare personnel consider prioritizing influenza vaccination for patients with recent cardiovascular diseases (CVDs) in light of new evidence.

Among a cohort of patients who received a flu vaccine, there was a 26% decreased risk of heart attacks and a 33% reduction in cardiovascular deaths, according to one study.1 These findings suggest a connection between influenza vaccination and reduced risk of cardiovascular diseases (CVDs).

While differing viewpoints exist regarding the impact of influenza vaccination on CVDs, some observational investigations have found a favorable connection between influenza vaccination and the reduction of cardiovascular incidents, such as acute myocardial infarction (MI).

This systemic review published in Scientific Reports, aimed to assess the possible association between influenza vaccination and a decreased likelihood of experiencing cardiovascular events.1

“Revealing a compelling insight into the potential benefits of influenza vaccination, our comprehensive meta-analysis, based on the latest randomized controlled trial (RCT) data, demonstrates a significant interaction between influenza vaccination and the reduction of major cardiovascular events,” wrote the researchers of the study. “Notably, patients who received the influenza vaccine experienced a remarkable risk reduction of over 20% in cardiovascular death.”

The researchers conducted a search of 275 English-literature studies using PubMed/MEDLINE, EMBASE, and the Cochrane CENTRAL databases through August 1, 2023, using the search terms ‘myocardial disease’ and ‘influenza vaccines.’ The review was conducted on RCTs exploring the potential link between influenza vaccination and the subsequent risk of developing CVDs.

Participants in the analysis had a diagnosis of CVD and the outcome was lower risk of cardiovascular events. Conference abstracts, case reports, and studies comparing high and low doses of influenza vaccination were excluded from the analysis.

The final analysis of 5 studies included 4529 patients who received the flu vaccine and 4530 patients who received a placebo. The average age of participants was 61 years. The study follow-up lasted an average of 9 months.

Of these participants, a total of 517 individuals experienced significant cardiovascular events compared with 621 cases among individuals who were administered a placebo (risk ratio [RR], 0.70; 95% CI, 0.55-0.91). Additionally, there was a decreased risk of heart attacks in vaccinated patients (RR, 0.74; 95% CI, 0.56-0.97) and a significant reduction in cardiovascular death events (RR, 0.67; 95% CI, 0.45-0.98).

These findings revealed a significant link between influenza vaccination and the reduction of major cardiovascular events among patients with recent cardiovascular diseases, in which there may be potential benefits of targeting this high-risk group for vaccination.

Regarding the potential mechanisms behind why vaccination protects heart health, the researchers note the possibilities of lowering inflammation caused by influenza, preventing secondary infections, and ensuring the stability of atherosclerotic plaque, which can become destabilized during the flu.

However, the researchers believe that further research is needed to better understand the precise mechanisms driving this association and to understand the potential long-term impact of influenza vaccination on cardiovascular outcomes.

“In the meantime, health care providers and policymakers should take heed of these findings and consider prioritizing influenza vaccination for patients with recent CVDs as a feasible and potentially life-saving preventive measure,” wrote the researchers.

This article originally appeared in AJMC.

1. Omidi F, Zangiabadian M, Shahidi Bonjar AH, et al. Influenza vaccination and major cardiovascular risk: a systematic review and meta-analysis of clinical trials studies. Sci Rep. Published online November 19, 2023. doi:10.1038/s41598-023-47690-9
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