Increased influenza activity may be associated with an increase in the number of heart failure hospitalisations1

Two self-controlled case series studies have previously demonstrated an increased risk of myocardial infarction when preceded by an acute respiratory infection, particularly in the week before an event.2,3 More recently, this was further supported by a study that found that a monthly increase of 5% in absolute influenza activity was associated with a 24% increase in heart failure hospitalisation rates within the same month.1 Cardiovascular events are a growing cause of mortality, with an increase of 21.1% in total deaths caused by cardiovascular diseases between 2007 and 2017.4,5


Recent evidence has shown that influenza may trigger severe cardiovascular complications, beyond respiratory infection6

A recent self-controlled case series study showed that adults aged 40 years and older, without a history of heart attack or stroke, were at a significantly increased risk of severe cardiovascular complication in the 1-3 days following a confirmed influenza infection.6

In the 1-3 days following a laboratory confirmed influenza infection, patients were at a:

  • 10x incrased risk of a first heart attack.6
  • 8x increased risk of a first stroke.6

How can influenza lead to an increase in cardiovascular incidents?

The strength and temporal pattern of the association between acute infections and an increased risk of cardiovascular incidents, may suggest a causal relationship.7


3 potential mechanisms by which influenza may contribute to increased cardiovascular incidents have been proposed:7-9

  • Systemic immune stimulation and inflammation may trigger disruption of atherosclerotic plaques, leading to myocardial infarction or stroke.7-9

  • Increased metabolic demands of peripheral tissues and organs may lead to insufficient cardiac oxygen supply and myocardial demand ischaemia.7-9

  • Direct heart tissue or arterial damage may increase the risk of heart failure.7-9



In a meta-analysis of 6 randomised clinical trials with a total of 6,735 patients (mean age 67 years), influenza vaccination reduced the risk of major cardiovascular events by 36%.10

Additionally, in a cohort-study of 134,048 patients aged over 18 years with heart-failure, influenza vaccination was associated with a 18% reduction in both cardiovascular and all-cause mortality.11

A review of systemic studies on prevention of acute myocardial infarction, reported a 15–45% efficacy of influenza vaccines; a range similar to other routine coronary prevention measures, including smoking cessation (32–43%), statins (19–30%) and hypertensive therapy (17–25%).12

Influenza vaccination may therefore prevent more than just respiratory disease, it may also help reduce the risk of serious cardiovascular complications.1012


  1. Kytömaa S, et al. Association of influenza-like illness activity with hospitalisations for heart failure: the atherosclerosis risk in communities study. JAMA Cardiol 2019; 1;4(4):363–369.

  2. Kwong JC, et al. Acute myocardial infarction after laboratory-confirmed influenza infection. N Engl J Med 2018; 378:345–353.

  3. Smeeth L, et al. Risk of myocardial infarction and stroke after acute infection or vaccination. N Engl J Med 2004; 351:2611–2618.

  4. GBD 2017 Causes of Death Collaborators. Global, regional and national age-sex-specific mortality for 282 causes of death in 195 countries and territories, 1980–2017: a systemic analysis for the Global Burden of Disease Study in 2017. Lancet 2018; 392(10159):1736–1788.

  5. GBD 2017 Study Highlights. Causes of death infographic: global trends in cause of death. 2018. Available from: [Last accessed October 2020].

  6. Warren-Gash C, et al. Laboratory-confirmed respiratory infections as triggers for acute myocardial infarction and stroke: a self-controlled case series analysis of national linked datasets from Scotland. Eur Respir J 2018; 51(3):1701794.

  7. Musher DM, et al. Acute infection, and myocardial infarction. N Eng J Med 2019; 380(2):171–176.

  8. Udell JA, et al. Does influenza vaccination influence cardiovascular complications? Expert Rev Cardiovasc 2015; 13(6):593–596.

  9. Vardeny O, et al. Influenza vaccination: a one-shot deal to reduce cardiovascular events. Eur Heart J 2017; 38(5):334–337.

  10. Udell JA, et al. Association between influenza vaccination and cardiovascular outcomes in high-risk patients: a meta-analysis. JAMA 2013; 310(16):1711–1720.

  11. Modin D, et al. Influenza vaccine in heart failure. Circulation 2019; 29:139(5):575–586.

  12. MacIntyre CR, et al. Influenza vaccination as a coronary intervention for prevention of myocardial infarction. Heart 2016; 102(24): 1953–1956.



MAT-GB-2002850(v1.0) | October 2020