Flu vaccination reduces composite of death, MI or stent thrombosis after MI

IAMI: Influenza Vaccination after Myocardial Infarction randomised trial

News - Aug. 30, 2021

Presented at the ESC congress 2021 by: Prof. Ole Fröbert, MD, PhD - Örebro, Sweden

Introduction and methods

The Influenza Vaccination after Myocardial Infarction (IAMI) trial aimed to determine whether in-hospital influenza vaccination improves clinical outcomes in patients with recent MI or high-risk coronary disease.

IAMI was a randomized, double-blind, placebo-controlled, multicenter trial which was conducted at 30 hospitals in 8 countries (Sweden, Denmark, Norway, Latvia, UK, Czech Republic, Bangladesh and Australia) over 4 influenza seasons (October 2016 through February 2020). Target enrollment was 4400 patients. However, the data safety and monitoring board recommended to terminate the study prematurely after enrollment of 2571 patients (58% of target) due to the COVID-19 pandemic. Participants were randomized in a 1:1 ratio to receive a influenza vaccine or placebo within 72 hours of an invasive coronary procedure or hospitalization. Average age was 60 years and 18% were women. The primary endpoint was the composite of all cause death, MI or stent thrombosis at 12 months. Key secondary endpoints included all cause death, CV death and MI.

Main results

  • The primary composite endpoint of all cause death, MI or stent thrombosis at 12 months occurred in 67 patients (5.3%) in the influenza vaccine group and in 91 (7.2%) in the placebo group (HR 0.72, 95%CI 0.52-0.99, P=0.040).
  • Analysis of key secondary endpoints showed that all-cause death (HR 0.59, 95%CI 0.39-0.89, P=0.010) and CV death (HR 0.59, 95%CI 0.39-0.90, P=0.014) were significantly reduced in the influenza vaccine group, compared to the placebo group. There was no difference between groups for the secondary endpoint of MI (HR 0.86, 95%CI 0.50-1.46, P=0.57).
  • Serious adverse events were rare and of similar incidence and type in both groups.


This randomized, placebo-controlled study showed that influenza vaccination after MI or in high risk CHD resulted in a reduced risk of the composite of all-cause death, MI or stent thrombosis at 12 months, compared to placebo.

Prof. Ole Fröbert said: “Our findings suggest that influenza vaccination should be considered as part of in-hospital treatment after myocardial infarction.”

  • Our reporting is based on the information provided at the ESC Congress -

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