Influence of ACEi and ARB use on HAI Response to Seasonal Influenza Vaccination

Background: Angiotensin Converting Enzyme Inhibitors (ACEi) and Angiotensin Receptor Blockers (ARB) have anti-inflammatory properties via decreasing AT1R binding/levels, reducing Reactive Oxygen Species (ROS) and cytokine activation. This study investigated whether these medications can negatively impact hemagglutination inhibition (HAI) responses to influenza vaccination. Methods: Participants, over the age of 18, were consented and enrolled in the study to receive an influenza vaccine during the 2024-2025 influenza season. Participants were classified into individuals on either ACEi or ARB. Healthy controls were selected based on age-sex-body mass index (BMI) matching and a second control group of participants were diagnosed with hypertension (HTN). but on taking these medications. Analysis focused on relative risk ratios (RR) for seroconversion to the influenza vaccine, in addition to day 28 geometric mean titers (GMT), number of seroprotected participants, and fold change was carried out. Results: We observed a lower trend of seroconversion amongst participants taking either medication compared to the HTN controls and did not observe any differences compared to the healthy controls. There were no differences in day 28 GMT, although the HTN controls had statistically significant higher fold changes in HAI titers compared to the healthy controls. Compared to the treatment groups, the HTN controls had a non-significant higher fold change against all three strains included in the influenza vaccine.