OBJECTIVES Influenza puts subjects of 50-64 years old at an increased risk of pneumonia, heart attack, and stroke and can lead to worsening of comorbid conditions such as diabetes, heart disease, and asthma. Real-world evidence studies have indicated that cell-based quadrivalent influenza vaccine (QIVc) reduced physician office visits and hospitalizations due to influenza compared with conventional egg-based quadrivalent influenza vaccine (QIVe). This study aimed to assess the relative vaccine effectiveness (rVE) of QIVc compared to QIVe to prevent influenza-related and respiratory-related hospitalizations/emergency room (ER) visits and all-cause hospitalizations, among subjects 50-64 years old during the 2017/18 influenza season.

METHODS A retrospective cohort analysis was conducted among subjects 50-64 years old vaccinated with QIVc or QIVe using administrative claims data in the U.S. (IQVIA’s Real-World Data Adjudicated Claims – US Database). Baseline characteristics included age, gender, payer type, geographic region, Charlson Comorbidity Index, comorbidities, month of flu vaccination, indicators of frail health status and pre-index hospitalization. The adjusted number of events and rates (per 1,000 vaccinated subject-seasons) of influenza-related hospitalizations/ER visits, respiratory-related hospitalizations/ER visits (e.g., pneumonia, asthma/COPD/bronchial and other respiratory events (e.g. sinusitis, respiratory tract infections, etc.)) and all-cause hospitalizations were calculated using inverse probability of treatment weighting (IPTW) and Poisson regression (following CMS/FDA statistical methodology).

RESULTS During the 2017/18 influenza season, an A/H3N2 predominant season; 245,316 recipients of QIVc and 831,368 of QIVe were identified following IPTW. Adjusted results show that rVE for QIVc was significantly higher compared to QIVe for influenza-related hospitalizations/ER visits (9.36% [95%CI: 0.31%-17.58%]) and all-cause hospitalization (5.09% [95%CI: 2.98%-7.16%]). Similar findings showed that QIVc was more effective than QIVe in preventing hospitalization/ER visits related to asthma/COPD/bronchial (6.49% [95%CI: 3.23%-9.64%]) and other respiratory events (5.80% [95%CI: 2.93%-8.59%]).

CONCLUSIONS QIVc reduced influenza-related and respiratory-related hospitalizations/ER visits and all-cause hospitalizations compared to QIVe in subjects 50-64 years old during 2017/18 influenza season.