Flu vaccine may reduce CV risk in high-risk individuals

Individuals at high risk for influenza who receive an influenza vaccination may have a reduced risk of cardiovascular (CV) events, according to a retrospective study presented at BCVS* 2020.

Data from the 2014 National Inpatient Sample Database was used to identify 7,056,314 hospitalized individuals at high risk for influenza and its subsequent complications as defined by the Centers for Disease Control and Prevention (CDC) criteria (ie, age ≥50 years, people with chronic medical conditions, patients with human immunodeficiency virus (HIV) or Acquired Immune Deficiency Syndrome (AIDS), living in nursing or long-term care facilities, native Americans and Alaskans, and obesity (body mass index [BMI] ≥30 kg/m²). Of these, 168,325 individuals had received influenza vaccination while hospitalized.

Individuals aged ≥50 years were less likely to have received an influenza vaccination compared with the general population (1.8 percent vs 15.3 percent). Lower vaccination rates were noted for patients with HIV/AIDS compared with those without these conditions (2.21 percent vs 8.2 percent), those living in nursing or long-term care facilities vs those living independently (1.8 percent vs 9.5 percent), and those with obesity vs those with a healthy weight (2.4 percent vs 9 percent).

Individuals aged ≥50 years who were vaccinated had a significantly reduced risk of myocardial infarction (MI; prevalence ratio [PR], 0.72), death during hospitalization (PR, 0.27), transient ischaemia (PR, 0.53), and cardiac arrest (PR, 0.15; p<0.0001 for all) in the 1-year post-vaccination. [BCVS 2020, abstract 398]

Individuals residing in nursing or long-term care facilities who were vaccinated also had a significantly reduced risk of MI (PR, 0.86; p=0.003) and transient ischaemia (PR, 0.44; p<0.0001), but not cardiac arrest (PR, 0.65; p=0.672). Receipt of influenza vaccination among Native Americans and Alaskans was associated with a reduced risk of MI (PR, 0.16), death during hospitalization (PR, 0.07), and transient ischaemia (PR, 0.13; p<0.0001 for all), as was the case with individuals who were obese (PR, 0.59, 0.24, and 0.45 for MI, death during hospitalization, and transient ischaemia, respectively; p<0.0001 for all).

Conversely, receipt of influenza vaccination did not significantly reduce the risk of MI (PR, 0.76; p=0.591), death during hospitalization (PR, 0.22; p=0.138), or transient ischaemia (PR, 0.77; p=0.651) among individuals with HIV/AIDS.

The low rate of influenza vaccination in these high-risk groups needs addressing, said lead author Roshni A. Mandania, a medical student at Texas Tech University Health Sciences Center Paul L. Foster School of Medicine in El Paso, Texas, US.

“These groups should have the highest vaccination rates because they are the most at risk; however, our findings show the opposite – flu vaccinations are underutilized. As healthcare providers, we must do everything we can to ensure our most vulnerable populations are protected against the flu and its serious complications,” she said.

Mandania noted that the flu vaccination rates in this study were specific to those administered in hospital and did not account for vaccinations received in the outpatient setting.

“Some people don’t view flu vaccinations as necessary or important [but] the results we found are staggering. It’s hard to ignore the positive effect the flu vaccine can have on serious cardiac complications,” she added.

“[F]or patients who have chronic diseases like high blood pressure, diabetes, or emphysema, it is critically important to get the annual flu vaccine. The potentially serious complications of the flu are far, far greater for those with chronic diseases,” pointed out Dr Eduardo Sanchez, Chief Medical Officer for Prevention at the American Heart Association, who was not affiliated with the study.