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Recruiting NCT06029933

Fluad vs. Fluzone High-Dose Vaccine Effectiveness Among Adults ≥65 Years

— Observational Influenza Community-acquired Pneumonia Cardiovascular Events

For patients and families

In plain language

An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.

What is being studied
The protocol lists: Adjuvanted Quadrivalent Inactivated Influenza Vaccine (aIIV4), High-Dose Quadrivalent Inactivated Influenza Vaccine (HD-IIV4).
Who it may be relevant to
Registry conditions: Influenza, Community-acquired Pneumonia, Cardiovascular Events. Basic parameters: from 65 years · All.
What needs checking
Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
Where it takes place
United States
Next step
Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →

Unsure about the terms? Read our patient guide →

Official title

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

Overview

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.

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.

Primary outcome measures

  • PCR-confirmed influenza [Time frame: ≥14 days after vaccination until date of outcome, death, loss-to-follow-up, or end of each season (estimated May 2024, May 2025, or May 2027)]
Secondary outcome measures (3)
  • Emergency department visit or hospitalization for PCR-confirmed influenza [Time frame: ≥14 days after vaccination until date of outcome, death, loss-to-follow-up, or end of each season (estimated May 2024, May 2025, or May 2027)]
  • Hospitalization for PCR-confirmed influenza [Time frame: ≥14 days after vaccination until date of outcome, death, loss-to-follow-up, or end of each season (estimated May 2024, May 2025, or May 2027)]
  • Hospitalization for all-cause community-acquired pneumonia [Time frame: ≥14 days after vaccination until date of outcome, death, loss-to-follow-up, or end of each season (estimated May 2024, May 2025, or May 2027)]

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

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Observational model
Cohort

Study locations

United States · 1 center
  • Kaiser Permanente Northern California (entire region) — Oakland

Publications

  • Hsiao A, Leong T, Fireman B, Hansen J, Zerbo O, Jacobson KB, Liao LD, Haag MDM, McGovern I, Zhang B, Dang J, Klein NP. Adjuvanted vs High-Dose Influenza Vaccines in Older US Adults: A Cluster Randomized Crossover Study. JAMA Netw Open. 2026 May 1;9(5):e2610120. doi: 10.1001/jamanetworkopen.2026.10120. PMID 42081247

Identifiers

NCT: NCT06029933 · 2033496

Primary sources (government registries)

View this study on ClinicalTrials.gov ↗