Relative Vaccine Effectiveness of Adjuvanted Inactivated Influenza Vaccine (aIIV) vs High-Dose Inactivated Influenza Vaccine (HD-IIV) for Prevention of Lab-Confirmed Influenza Among Adults ≥65 Years of Age in the United States

Kaiser Permanente

Summary

This study will evaluate the relative vaccine effectiveness of quadrivalent adjuvanted inactivated influenza vaccine (aIIV4) versus quadrivalent high-dose inactivated influenza vaccine (HD-IIV4) in preventing polymerase chain reaction (PCR)-confirmed influenza and influenza-related outcomes in adults ≥65 years of age during the 2023/24, 2024/25, and 2026/27 influenza seasons. The study is an observational study conducted at Kaiser Permanente Northern California (KPNC), an integrated health care system in the United States.

Eligibility

Age range: 65+ years
Sex: All
Healthy volunteers: Yes

Detailed criteria

Inclusion Criteria: * Age ≥65 years at the time of influenza vaccination * KPNC member at the time of vaccination * Receive either aIIV4 or HD-IIV4 at a KPNC facility during the 2023/24 and/or 2024/25 influenza seasons Exclusion Criteria: * Age \<65 years at the time of influenza vaccination * Received either aIIV4 or HD-IIV4 in the inpatient setting * Receive more than one influenza vaccination during a single season period (i.e., 2023/24 or 2024/25 influenza seasons) * Receive an influenza vaccination outside of KPNC

Interventions

Biological
Adjuvanted Quadrivalent Inactivated Influenza Vaccine (aIIV4)
Fluad Quadrivalent vaccine is an inactivated influenza vaccine formulated to contain 60 mcg of hemagglutinin (HA) total, with 15 mcg from each of the four recommended influenza strains and the MF59 adjuvant in single-dose prefilled 0.5 mL syringes. Kaiser Permanente Northern California members ≥65 years may receive Fluad as part of routine clinical care during the influenza season.
Biological
High-Dose Quadrivalent Inactivated Influenza Vaccine (HD-IIV4)
Fluzone High-Dose Quadrivalent vaccine is an inactivated split virion influenza vaccine formulated to contain 240 mcg of HA total, with 60 mcg from each of the four recommended influenza strains in single-dose prefilled 0.7 mL syringes. Kaiser Permanente Northern California members ≥65 years may receive Fluzone High-Dose as part of routine clinical care during the influenza season.

Location

Kaiser Permanente Northern California (entire region)
Oakland, California
Amber.Hyman@kp.org (510) 267-7517

Summary

Eligibility

Age range

65+ years

Sex

All

Healthy volunteers

Yes

Detailed criteria

Interventions

Biological

Adjuvanted Quadrivalent Inactivated Influenza Vaccine (aIIV4)

Fluad Quadrivalent vaccine is an inactivated influenza vaccine formulated to contain 60 mcg of hemagglutinin (HA) total, with 15 mcg from each of the four recommended influenza strains and the MF59 adjuvant in single-dose prefilled 0.5 mL syringes. Kaiser Permanente Northern California members ≥65 years may receive Fluad as part of routine clinical care during the influenza season.

Biological

High-Dose Quadrivalent Inactivated Influenza Vaccine (HD-IIV4)

Fluzone High-Dose Quadrivalent vaccine is an inactivated split virion influenza vaccine formulated to contain 240 mcg of HA total, with 60 mcg from each of the four recommended influenza strains in single-dose prefilled 0.7 mL syringes. Kaiser Permanente Northern California members ≥65 years may receive Fluzone High-Dose as part of routine clinical care during the influenza season.