A high-dose flu vaccine may not help protect heart patients from cardiopulmonary death and hospitalization, according to research presented Tuesday at the American Heart Association’s Scientific Sessions 2020.

Among 5,000 heart attack and heart failure patients across 157 clinical sites in the United States and Canada, the high-dose, trivalent influenza vaccine was no more effective at preventing these outcomes than the standard-dose quadrivalent vaccine, reported Orly Vardeny, PharmD, of University of Minnesota Medical School.

There may be several explanations for the findings, Vardeny and colleagues said. It is possible that both the high-dose and standard dose vaccines reduced heart and lung hospitalizations equally. Another possibility is that since participants already were at a very high risk for hospitalization, and most hospitalizations were not due to influenza, any benefit from a high-dose vaccine would not have overcome the underlying risk in this group, she explained. 

An extra influenza strain also was present in the standard-dose vaccine. This might have offset the benefit of the higher dose, Vardeny added.

Most importantly, the current study shows that vaccine dose may not be as important as getting vaccinated, she added.

“The data don’t detract from the extremely strong recommendation that all patients with heart disease get vaccinated for influenza,” she said. “This is especially the case this year, when influenza will be co-circulating with SARS-CoV-2, the virus that causes COVID-19.”

Vardely foresees more research on the protectiveness of specific vaccines in patients with high-risk conditions and also on whether the high-dose vaccine is more effective in lower-risk cardiac patients.