Growing evidence that influenza vaccine protects against cardiovascular diseases

Quebec researchers are drawing attention to the mounting evidence on the protective effect of influenza vaccines against cardiovascular diseases, particularly in high-risk adults. They believe that greater recognition of this preventive effect could help with vaccine uptake when promoting the value of influenza vaccination to the public. Influenza infections are associated with an increased risk of adverse cardiovascular events in adults, including sudden death, myocardial infarction, heart failure, cardiac arrhythmia and stroke. Several biological mechanisms might explain how influenza infection could trigger cardiovascular disease: induction of pro-inflammatory changes in the cellular composition of atherosclerotic lesions induction of a persistent procoagulant state, including platelet activation increased metabolic needs of peripheral tissues and organs, which compromises arterial perfusion infection and inflammation of myocardial cells, which disturb cardiac function. The authors identified 28 systematic reviews (with or without meta-analysis) on the protective effect of influenza vaccination on cardiovascular disease. Seven of these reviews were published in 2022–2023. The most comprehensive review covered 33 studies. Out of 52 comparisons reported in the review, 40 showed a statistically significant reduction in risk, 11 showed a nonstatistically significant reduction in risk, and one showed a nonstatistically significant increased risk of 2% for stroke. Evidence is particularly strong for prevention of cardiac events in high-risk patients, with four randomized clinical trials showing a 45% decrease in risk of major adverse cardiovascular events (cardiovascular death or hospitalization for myocardial infarction, unstable angina, stroke, heart failure, or urgent coronary revascularization) among patients with a history of coronary disease (within 12 months of follow-up). The authors provide a table summarizing the results of 10 meta-analyses published in 2022–2023 relating to the effect of influenza vaccines on cardiovascular disease in adults. Most results leaned towards a protective effect of influenza vaccine. The evidence is very robust for prevention of cardiovascular deaths and nonfatal myocardial infarction in high-risk individuals, but lower for heart failure, arrhythmia and stroke, and also lower for all cardiovascular outcomes in low-risk adults. The authors note that the cardiovascular protective effect of influenza vaccine is not yet mentioned in the Canadian Immunization Guide and is likely not known by a majority of vaccinators. The information outlined in their article is intended to alert the Canadian public health community about this issue. The cardiovascular benefits of influenza vaccine could be used to promote the usefulness of influenza vaccines to the public. Mentioning this potential benefit may change public perception of the usefulness of influenza vaccine and increase vaccine uptake. Reference 1. De Wals P, Desjardins M. Influenza vaccines may protect against cardiovascular diseases: the evidence is mounting and should be known by the Canadian public health community. CCDR 2023;49(10):433-8. (accessed November 30, 2023).

Growing evidence that influenza vaccine protects against cardiovascular diseases

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