Flu Vaccine Underutilized, Provides Potential CV Benefit in High Risk Patients

Roshni Mandania, BS

New research presented at the American Heart Association (AHA)’s Basic Cardiovascular Sciences (BCVS) 2020 Scientific Sessions links seasonal flu vaccinations to a decrease in risk for a slew of adverse cardiovascular events, including heart attack and stroke.

Investigators from the study suggest the results underscore the importance of seasonal flu vaccinations and overall vigilance in the care of elderly patients.

"These groups should have the highest vaccination rates because they are the most at risk; however, our findings show the opposite - flu vaccinations are under-utilized," said lead investigator RoshniMandania, BS, a 2021 MD candidate at Texas Tech University Health Sciences Center Paul L. Foster School of Medicine, in a statement. "As health care providers, we must do everything we can to ensure our most vulnerable populations are protected against the flu and its serious complications."

While previous studies have suggested a similar link between seasonal flu vaccinations and a decrease in events such as myocardial infarction, investigators of the current study hoped to explore this association in patients at high risk for influenza. Under the guidance of Debabrata Mukherjee, MD, chief of Cardiovascular Services at Texas Tech University Medical Center, Mandania and a team of investigators designed aa retrospective cohort study using data from the 2014 National Inpatient Sample (NIS) database.

The ultimate aim of the study was to compare utilization and outcomes in high risk patients those who did receive vaccination during hospitalization versus those who did not. For the purpose of the analysis, investigators patients belonging to multiple high risk subgroups including adults 50 years and older, people with chronic medical conditions, AIDS patients, people at nursing facilities, American Indians and Alaskan natives, and obese people.

In total, the NIS database included 7,056,314 patients considered at high risk for influenza during 2014. Of these, only 168,325 received flu vaccinations during their hospitalization. Of note, the rate of vaccination in patients over 50 was less than 2% compared to a vaccination rate of 15.3% in the general population during that year.

Investigators also pointed out multiple associations between flu vaccinations among patients 50 years and older and reductions in risk of adverse cardiovascular events. Specifically, patients in the group receiving a seasonal influenza vaccination had a 28% lower risk of myocardial infarction, a 73% lower risk of death, a 47% lower risk of transient ischemic attack, and an 85% lower risk of cardiac arrest.

Additionally, nursing home residents had a vaccination rate of 1.8% compared to 9.5% for those who were living independently. Among obese patients, 2.4% of patients reported receiving a vaccination compared to 9% of patients with a healthy weight.

“The results we found are staggering. It’s hard to ignore the positive effect the flu vaccine can have on serious cardiac complications,” Mandania added in the aforementioned statement. “Some people don’t view flu vaccinations as necessary or important, and many may face barriers accessing health care including receiving the flu vaccine.”

In the statement from the AHA, investigators noted the design of their study—focusing solely on immunization occurring in the hospital—limits the generalizability of their findings, but purported results still provide valuable insight.

This study, “Magnitude and Impact of Underutilization of Flu Vaccine in High-Risk US Cohorts on Cardiovascular Events,” was presented at BCVS 2020.