Posted on 18 May 2022
Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.
Why is this research important: According to the World Health Organisation, influenza viruses cause between 290 000 and 650 000 deaths globally from respiratory problems, and many more will be hospitalised. This alone is a good incentive to get the annual flu vaccine, but some studies have suggested that getting vaccinated could have other benefits, such as protection against cardiovascular disease. Is this true, and if so, what are the possible explanations?
What did the researchers do: In this study, researchers conducted a meta-analysis of six clinical trials of flu vaccines conducted since the year 2000, which involved over 9000 people in total, aged 65.5 on average. A meta-analysis is where researchers analyse the results of multiple independent studies and look for trends in the data. In this case, they wanted to see if getting a flu vaccine reduced the probability of cardiovascular conditions or events like stroke or heart attack during the subsequent year.
Key takeaway(s) from this research: On average, receiving a flu vaccine was associated with a 34% reduced risk of having a major cardiovascular issue during the subsequent year. This number increased to 45% in patients with a recent history of heart problems. Overall, 1 cardiovascular event was prevented for every 56 vaccines given.
This was a meta-analysis of clinical trials, which means that every participant was randomly given either a flu vaccine or a placebo. This means that the results can’t be explained by healthier people being more likely to get vaccinated, suggesting that getting vaccinated against influenza does cause a significant reduction in cardiovascular events. The most likely explanation for this is also the most straightforward: flu infections increase the risk of cardiovascular events. Some studies suggest that the risk of heart attack is 6 times higher within a week of a confirmed flu infection. However, some studies also suggest that flu vaccines may interact with the immune system to help stabilise fatty plaques that build up in arteries, making them less likely to break up and cause a blood clot.
Regardless of the mechanism, we should be aware that flu vaccines protect not just against influenza, but also the complications that can occur as a result of the stress that infections can place on various organ systems. Of course, when it comes to heart disease, the benefits of vaccination are likely to be much lower in younger people.
Association of Influenza Vaccination With Cardiovascular Risk: http://jamanetwork.com/article.aspx?doi=10.1001/jamanetworkopen.2022.8873