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NCT Number: NCT06029933

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

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.

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Key information

Conditions

Influenza Cardiovascular Events Community-Acquired Infections Community-Acquired Pneumonia Infections Influenza, Human Orthomyxoviridae Infections Pneumonia RNA Virus Infections Respiratory Tract Diseases Respiratory Tract Infections Virus Diseases

Age range

65 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Kaiser Permanente Northern California (entire region)

Oakland, California, 94612, United States

Location status: Recruiting

Location contact

Amber H. Hyman, PhD, MPH

CONTACT

[email protected]

(510) 267-7517

Nicola P. Klein, MD, PhD

PRINCIPAL_INVESTIGATOR

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

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.

Other names: Fluad

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.

Other names: Fluzone High-Dose

Primary outcomes

  1. 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)

    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.

Secondary outcomes

  1. 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)

    KPNC members ≥65 years who receive Fluad or Fluzone High-Dose will be retrospectively assessed for an emergency department visit or hospitalization for 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 combined.

  2. 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)

    KPNC members ≥65 years who receive Fluad or Fluzone High-Dose will be retrospectively assessed for hospitalization for PCR-confirmed influenza. This outcome will be assessed in a pooled analysis across all seasons combined.

  3. 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)

    KPNC members ≥65 years who receive Fluad or Fluzone High-Dose will be retrospectively assessed for hospitalization for all-cause community-acquired pneumonia. This outcome will be assessed in single-season analyses (2023/24, 2024/25, and 2026/27 separately) and a pooled analysis across all seasons combined.

Other outcomes

  1. Hospitalization for cardiovascular events

    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)

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

  2. PCR-confirmed influenza in subgroups with comorbidities

    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)

    KPNC members ≥65 years with comorbidities (e.g., cardiovascular and respiratory conditions, diabetes, obesity) who receive Fluad or Fluzone High-Dose will be retrospectively assessed for hospitalization for PCR-confirmed influenza. This outcome will be assessed in a pooled analysis across all seasons combined.

Study contacts

Contact information is provided by the study sponsor or research team.

Amber H. Hyman, PhD, MPH

CONTACT

[email protected]

510-267-7571

Sponsors and collaborators

Lead sponsor

Kaiser Permanente

Other

Collaborators

  • Seqirus

Registry information

Official study 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

Important dates

Study start
2023
Primary completion
2027
Study completion
2028
First posted
Sep 8, 2023
Registry last updated
Aug 5, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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