Disparities in Influenza Vaccination-Opportunity to Extend Cardiovascular Prevention to Millions of Hearts

Moving the Needle on Atherosclerotic Cardiovascular Disease and Heart Failure with Influenza Vaccination

PURPOSE OF REVIEW

The interplay between viral respiratory infections and cardiovascular disease has been most comprehensively researched using seasonal and pandemic influenza viruses as case studies. Here, we summarize the latest international observational research and clinical trials that examined the association between influenza, influenza vaccines, and cardiovascular disease, while contextualizing their findings within those of landmark studies.

RECENT FINDINGS

Most recent observational literature found that one in eight adults hospitalized with laboratory-confirmed influenza infection experienced an acute cardiovascular event. The latest meta-analysis of the cardioprotective effects of influenza vaccine found a 25% reduced risk of all-cause death. There are four large cardiovascular outcome trials assessing the cardioprotective effects of different influenza vaccine strategies. Among these, the INVESTED study showed there is no significant difference between the high-dose trivalent and standard-dose quadrivalent influenza vaccines in reducing all-cause mortality or cardiopulmonary hospitalizations in a high-risk patient group with pre-existing cardiovascular disease. Persons with cardiovascular disease represent a high priority group for viral vaccines; hence, using robust evidence to increase vaccine confidence among patients and practitioners is integral as we prepare for a possible influenza resurgence in the coming years.

Influenza vaccination: a 'shot' at INVESTing in cardiovascular health

The link between viral respiratory infection and non-pulmonary organ-specific injury, including cardiac injury, has become increasingly appreciated during the current coronavirus disease 2019 (COVID-19) pandemic. Even prior to the pandemic, however, the association between acute infection with influenza and elevated cardiovascular risk was evident. The recently published results of the NHLBI-funded INfluenza Vaccine to Effectively Stop CardioThoracic Events and Decompensated (INVESTED) trial, a 5200 patient comparative effectiveness study of high-dose vs. standard-dose influenza vaccine to reduce cardiopulmonary events and mortality in a high-risk cardiovascular population, found no difference between strategies. However, the broader implications of influenza vaccine as a strategy to reduce morbidity in high-risk patients remain extremely important, with randomized controlled trial and observational data supporting vaccination in high-risk patients with cardiovascular disease. Given a favourable risk-benefit profile and widespread availability at generally low cost, we contend that influenza vaccination should remain a centrepiece of cardiovascular risk mitigation and describe the broader context of underutilization of this strategy. Few therapeutics in medicine offer seasonal efficacy from a single administration with generally mild, transient side effects, and exceedingly low rates of serious adverse effects. Infection control measures such as physical distancing, hand washing, and the use of masks during the COVID-19 pandemic have already been associated with substantially curtailed incidence of influenza outbreaks across the globe. Appending annual influenza vaccination to these measures represents an important public health and moral imperative.