Dr. Boikos is an epidemiologist and medical affairs professional with graduate degrees in Public Health (MScPH) and Epidemiology (PhD) from McGill University. She is experienced in the design and analysis of complex epidemiological studies. A medical affairs professional at Seqirus Inc. Dr. Boikos has conceptualized, designed and participated in the conduct of influenza vaccine outcome trials in their Center for Outcomes Research and Evaluation.
Real-world effectiveness of adjuvanted and high-dose trivalent, and quadrivalent influenza vaccine in adults ≥65 during the 2019-2020 us influenza season
Constantina Boikos, Seqirus Inc., Quebec
Mahrukh Imran, Seqirus Inc., Quebec
Juan Puig-Barbera, FISABIO, Spain
Justin Ortiz, University of Maryland School of Medicine, USA
Lauren Fisher, Veradigm, USA
Dan O’Brien, Veradigm, USA
Machaon Bonafede, Veradigm, USA
James A. Mansi, Seqirus Inc., Quebec
Age-related immunosenescence may impair immune responses to influenza vaccination in older adults. MF59-adjuvanted trivalent inactivated influenza vaccine (adjuvanted-IIV3) elicits greater immune responses compared with nonadjuvanted influenza vaccines. This study estimated the relative vaccine effectiveness (rVE) of adjuvanted-IIV3 vs egg-derived, quadrivalent inactivated influenza vaccine (IIV4e) and high-dose trivalent inactivated influenza vaccine (HD-IIV3) in preventing inpatient or outpatient influenza-related medical encounters (IRME) in the 2019-2020 US season in a real-world setting.
We conducted a retrospective cohort study using electronic medical records linked to pharmacy and medical claims during the influenza season, defined as August 1, 2019, through March 7, 2020. The influenza season was truncated at March 7, 2020 to avoid potential bias arising from the co-circulation of SARS-CoV-2 in the US in March 2020. Individuals of 65 years and older with a record of vaccination with adjuvanted-IIV3, IIV4, or HD-IIV3 were included in the analysis. The primary outcome was influenza-related medical encounters (IRME), defined by diagnostic codes specific to influenza illness (ICD-10 codes J09*–J11*). A doubly robust, inverse probability of treatment weighting methodology was used to obtain odds ratios (ORs) adjusted for age, sex, race, ethnicity, geographic region, vaccination week, health status, frailty, and prior healthcare resource utilization. rVE was determined using the formula (1-ORadjusted)*100. An exploratory analysis evaluated rVE separately for inpatient and outpatient IRME. Sensitivity analyses were conducted using alternative influenza season cutoff dates.
The study included 936,508, 651,034, and 1,813,819 recipients of adjuvanted-IIV3, IIV4, and HD-IIV3. Adjusted rVE of adjuvanted-IIV3 in preventing IRME in either inpatient or outpatient settings was 27.5% (95% CI: 24.4%-30.5%) vs IIV4 and 13.9% (95% CI: 10.7%-17.0%) vs HD-IIV3 (Figure 1). For inpatient IRMEs, the rVE was 17.1% (95% CI: 10.6%-23.2%) vs IIV4 and 6.5% (95% CI: 0.1%-12.4%) vs HD-IIV3, and for IRME outpatient visits, 31.3% (95% CI: 27.8%-34.6%) and 16.9% (95% CI: 13.2%-20.4%), respectively (Figure 2). Similar trends were observed in subgroup analyses by age (Figure 1). Results were consistent when using alternative cutoff dates for the 2019-2020 U.S. influenza season.
In this real-world study, a cohort of over 3 million influenza vaccine recipients, significantly fewer IRMEs occurred in adults ≥65 years vaccinated with adjuvanted-IIV3 compared with IIV4e or HD-IIV3 during the 2019-2020 US influenza season, with larger effect estimates observed in the comparison against IIV4e as expected. Findings from this study are aligned with previously published research and provide further evidence supporting the relative effectiveness of adjuvanted-IIV3.