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| Name | Class |
|---|---|
| Seqirus | INDUSTRY |
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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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Fluad Recipients | Kaiser Permanente Northern California members aged ≥65 years who receive 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) |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| 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. |
| Measure | Description | Time Frame |
|---|---|---|
| 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 and 2024/25 separately) and a pooled 2-seasons analysis (2023/24 and 2024/25 combined). | ≥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 | Description | Time Frame |
|---|---|---|
| Emergency department visit or hospitalization for PCR-confirmed influenza | 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 and 2024/25 separately) and a pooled 2-seasons analysis (2023/24 and 2024/25 combined). |
| Measure | Description | Time Frame |
|---|---|---|
| Hospitalization for cardiovascular events | 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 and 2024/25 separately) and a pooled 2-seasons analysis (2023/24 and 2024/25 combined). | ≥14 days after vaccination until date of outcome, death, loss-to-follow-up, or end of each season (estimated May 2024 or May 2025) |
Inclusion Criteria:
Exclusion Criteria:
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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.
| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Amber H. Hyman, PhD, MPH | Contact | 510-267-7571 | Amber.Hyman@kp.org |
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Kaiser Permanente Northern California (entire region) | Recruiting | Oakland | California | 94612 | United States |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 42081247 | Derived | 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. |
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| ID | Term |
|---|---|
| D007251 | Influenza, Human |
| D000098968 | Community-Acquired Pneumonia |
| ID | Term |
|---|---|
| D012141 | Respiratory Tract Infections |
| D007239 | Infections |
| D009976 | Orthomyxoviridae Infections |
| D012327 | RNA Virus Infections |
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| ID | Term |
|---|---|
| C478243 | fluad vaccine |
| D007252 | Influenza Vaccines |
| C000618615 | Fluzone High-Dose |
| ID | Term |
|---|---|
| D014765 | Viral Vaccines |
| D014612 | Vaccines |
| D001688 | Biological Products |
| D045424 | Complex Mixtures |
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| 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. |
|
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| ≥14 days after vaccination until date of outcome, death, loss-to-follow-up, or end of each season (estimated May 2024 or May 2025) |
| Hospitalization for PCR-confirmed influenza | 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 2-seasons analysis (2023/24 and 2024/25 combined). | ≥14 days after vaccination until date of outcome, death, loss-to-follow-up, or end of each season (estimated May 2024 or May 2025) |
| Hospitalization for all-cause community-acquired pneumonia | 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 and 2024/25 separately) and a pooled 2-seasons analysis (2023/24 and 2024/25 combined). | ≥14 days after vaccination until date of outcome, death, loss-to-follow-up, or end of each season (estimated May 2024 or May 2025) |
| PCR-confirmed influenza in subgroups with comorbidities | 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 2-seasons analysis (2023/24 and 2024/25 combined). | ≥14 days after vaccination until date of outcome, death, loss-to-follow-up, or end of each season (estimated May 2024 or May 2025) |
| D014777 | Virus Diseases |
| D012140 | Respiratory Tract Diseases |
| D017714 | Community-Acquired Infections |
| D011014 | Pneumonia |