Seasonal influenza vaccine development and mass production may lead to future efforts targeted at developing and evaluating vaccine strategies for Covid-19, say researchers.
In the study, published in the Journal of the American College of Cardiology, the research team evaluated whether existing flu trial networks could offer primary and secondary prevention strategies for patients with cardiovascular disease at risk of complications from Covid-19.
The World Health Organisation (WHO) estimates that influenza kills as many as 6,50,000 people every year globally, citing influenza as a top 10 leading cause of death among people of all ages, especially those with one or more comorbidities like cardiovascular disease.
Furthermore, seasonal influenza epidemics have been associated with population-level increases in cardiovascular hospitalisation and mortality.
For these reasons, clinical guidelines recommend the general population receive their flu vaccination annually to reduce the risk of influenza-like illness, with high-risk individuals the most urged to get vaccinated.
Research has shown that viral respiratory infections such as seasonal influenza and Covid-19 are risk factors for cardiovascular disease.
Patients with cardiovascular disease are also at a higher risk of complications following viral respiratory infections, including increased morbidity, mortality and health care utilization.
Current data suggests influenza infection and the novel coronavirus share similar symptoms at the outset, primarily fever, cough and shortness of breath. However, Covid-19 appears to be more contagious than the flu.
“Although Covid-19 and other respiratory virus infections are associated with acute myocardial infarction and other cardiovascular events, influenza has the best evidence of a safe vaccine option for cardiovascular risk reduction to date,” said study author Jacob A. Udell from the University of Toronto in Canada.
Several observational and small, randomized studies have suggested that influenza vaccination may serve as a preventative measure against adverse cardiovascular outcomes.
However, despite international guidelines recommending routine influenza and pneumococcal vaccination for patients with cardiovascular disease, uptake is substantially lacking and often deprioritised, including at the time of cardiovascular hospitalisation.
There are currently three international cardiovascular outcome trials examining the cardioprotective effects of different influenza vaccine formulations, according to the team.
“Three large ongoing influenza vaccine cardiovascular outcome trials have an opportunity to contribute further to our understanding of the underlying comorbidities in these patients that may be driving morbidity and mortality associated with Covid-19 infection,” Udell said.
“While developing new vaccines, we will also definitively learn soon whether influenza vaccination is an effective, low-cost, widely available therapy that reduces cardiovascular risk, which may further help prevent fatal and nonfatal cardiovascular complications of Covid-19,” Udell noted.