Clinical trial NCT06029933: Fluad vs. Fluzone High-Dose Vaccine Effectiveness Among Adults ≥65 Years
Official title: Relative Vaccine Effectiveness of Adjuvanted Quadrivalent Inactivated Influenza Vaccine vs High-Dose Quadrivalent Inactivated Influenza Vaccine Among Adults ≥65 Years for the 2023-24 and 2024-25 Seasons
Study type: OBSERVATIONAL
Overall status: RECRUITING
Conditions: Influenza
Community-acquired Pneumonia
Cardiovascular Events
Lead sponsor: Kaiser Permanente
Sponsor class: OTHER
Collaborators: name: Seqirus
First posted: 2023-09-08
Enrollment: 960000
Sex: ALL
Minimum age (years): 65
Standard ages: OLDER_ADULT
Accepts healthy volunteers: yes
Observational model: COHORT
Time perspective: RETROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: This study includes KPNC adults ≥65 years who receive Fluad or Fluzone High-Dose influenza vaccine as part of routine clinical care during the 2023/24 and/or 2024/25 influenza seasons.

Brief 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 and 2024/25 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 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

Primary outcomes:
measure: PCR-confirmed influenza
timeFrame: ≥14 days after vaccination until date of outcome, death, loss-to-follow-up, or end of each season (estimated May 2024 or May 2025)
Secondary outcomes:
measure: Emergency department visit or hospitalization for PCR-confirmed influenza
timeFrame: ≥14 days after vaccination until date of outcome, death, loss-to-follow-up, or end of each season (estimated May 2024 or May 2025)
measure: Hospitalization for PCR-confirmed influenza
timeFrame: ≥14 days after vaccination until date of outcome, death, loss-to-follow-up, or end of each season (estimated May 2024 or May 2025)
measure: Hospitalization for all-cause community-acquired pneumonia
timeFrame: ≥14 days after vaccination until date of outcome, death, loss-to-follow-up, or end of each season (estimated May 2024 or May 2025)
Other outcomes:
measure: Hospitalization for cardiovascular events
timeFrame: ≥14 days after vaccination until date of outcome, death, loss-to-follow-up, or end of each season (estimated May 2024 or May 2025)
measure: PCR-confirmed influenza in subgroups with comorbidities
timeFrame: ≥14 days after vaccination until date of outcome, death, loss-to-follow-up, or end of each season (estimated May 2024 or May 2025)
Locations:
city: Oakland
country: United States
facility: Kaiser Permanente Northern California (entire region)
state: California
Study officials:
References: