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

NCT06029933 | Recruiting FDA Drug

• 1 other identifier: 2033496
• Study Type: observational
• Target: 1,500,000
• Locations: 1 country
• Sites: 1

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, 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.

Conditions

Influenza; Community-acquired Pneumonia; Cardiovascular Events

Outcome Measures

Primary Outcomes (1)

• PCR-confirmed influenza

  KPNC members ≥65 years who receive Fluad or Fluzone High-Dose will be retrospectively assessed for the presence of PCR-confirmed influenza. This outcome will be assessed in single-season analyses (2023/24, 2024/25, and 2026/27 separately) and a pooled analysis across all seasons.

  ≥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 Outcomes (3)

• Emergency department visit or hospitalization for PCR-confirmed influenza

  ≥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

  ≥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

  ≥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)

Other Outcomes (2)

• Hospitalization for cardiovascular events

  ≥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)

• PCR-confirmed influenza in subgroups with comorbidities

  ≥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)

Study Arms (2)

Fluad Recipients

Kaiser Permanente Northern California members aged ≥65 years who receive Adjuvanted Quadrivalent Inactivated Influenza Vaccine (aIIV4)

Biological: Adjuvanted Quadrivalent Inactivated Influenza Vaccine (aIIV4)

Fluzone High-Dose Recipients

Kaiser Permanente Northern California members aged ≥65 years who receive High-Dose Quadrivalent Inactivated Influenza Vaccine (HD-IIV4)

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

Interventions

Adjuvanted Quadrivalent Inactivated Influenza Vaccine (aIIV4) BIOLOGICAL

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.

Also known as: Fluad

Fluad Recipients

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

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.

Also known as: Fluzone High-Dose

Fluzone High-Dose Recipients

Eligibility Criteria

• Age: 65 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Older Adult (65+)
• 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, 2024/25, and/or 2026/27 influenza seasons.

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Kaiser Permanente: lead
• Seqirus: collaborator

Study Sites (1)

Kaiser Permanente Northern California (entire region)

Oakland, California, 94612, United States

RECRUITING

Related Publications (1)

• 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 DERIVED

MeSH Terms

Conditions

Influenza, Human; Community-Acquired Pneumonia

Interventions

fluad vaccine; Influenza Vaccines; Fluzone High-Dose

Condition Hierarchy (Ancestors)

Respiratory Tract Infections; Infections; Orthomyxoviridae Infections; RNA Virus Infections; Virus Diseases; Respiratory Tract Diseases; Community-Acquired Infections; Pneumonia

Intervention Hierarchy (Ancestors)

Viral Vaccines; Vaccines; Biological Products; Complex Mixtures

Central Study Contacts

Amber H. Hyman, PhD, MPH

CONTACT

510-267-7571; Amber.Hyman@kp.org

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: RETROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: August 28, 2023
• First Posted: September 8, 2023
• Study Start: August 17, 2023
• Primary Completion (Estimated): May 1, 2027
• Study Completion (Estimated): May 1, 2028
• Last Updated: August 5, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)