ST. LOUIS — A study published in JAMA Internal Medicine found that COVID-19 vaccination reduced the risk of major adverse cardiovascular events by 38 percent among certain patients. Clinical researcher Ziyad Al-Aly co-authored the study, which followed 1,039,659 patients in the St. Louis Health Care System who received seasonal flu shots between September 3, 2024, and December 31, 2024. Among these patients, 349,085 received both a flu shot and a COVID-19 vaccine, while 690,574 received only a flu shot. The reduction in cardiovascular events was most pronounced in patients aged 75 and older and those with chronic kidney or lung disease. The study authors estimated this reduction could prevent approximately 3,500 major cardiac events and 2,400 deaths annually per 1 million people.

The researchers estimated COVID-19 vaccination reduced the rate of associated major adverse cardiovascular events from approximately 5 per 10,000 to 3 per 10,000. "What that really means is that those events are actually likely related to SARS-CoV-2, that were never recognized to be so in the first place," Al-Aly said.

COVID-19 vaccination was associated with a 24 percent reduction in all-cause cardiac events. "Despite the fact that the virus has evolved and things have mellowed down, and we no longer think of Covid infection as consequential, there is still actually a tidal wave of SARS-CoV-2 that continues to circulate in the population. Much of it is only unrecognized, leading to heart problems. Much of it is unlinked or unattributed to SARS-CoV-2, because people are not testing," he said.

Cardiologist Robert Califf wrote an accompanying commentary on the study findings. "There are many studies now that show that vaccinations of various types seem to reduce the risk of chronic diseases, including cardiovascular disease, this is not inconsistent with what the other studies have shown," Califf said. He also stated that COVID-19 vaccination uptake in older adults is less than half of the uptake rate for flu vaccines. "Forgoing vaccinations, that is leaving a lot of protection on the table," Al-Aly said. Califf also said, "The evidence says that the benefits outweigh the risks. My general view for me and people I care about is to get the update, and for people who are high risk, definitely get the update."

Bill Hanage, a professor of epidemiology at Harvard University, said, "It is only recently that influenza has overtaken Covid as the most significant respiratory cause of illness and death in the United States. Those were pretty bad flu seasons. Covid vaccines are still protective and still keep people out of hospital." A study funded by the European Centre for Disease Prevention and Control found approximately 55 percent vaccine effectiveness against symptomatic disease in individuals aged 60 and older during the two months following vaccination.