Flublok v. Standard Dose Vaccine Effectiveness Among Kaiser Permanente Northern California Adults 18-64 Years

Examining Vaccine Effectiveness (VE) of Flublok Relative to Standard Dose Inactivated Influenza Vaccine Among Kaiser Permanente Northern California Members Aged 18-64 Years

The overall objective of this study is to describe the effectiveness of Flublok Quadrivalent vaccine compared to standard dose inactivated influenza vaccine (SD-IIV) in adults 18 through 64 years of age. During this study, Flublok Quadrivalent or SD-IIV will be administered according to the guidelines in the Prescribing Information materials and only to persons for whom it is indicated. The 2018-2019, 2019-2020, and 2020-2021 formulations of recombinant influenza vaccine (Flublok Quadrivalent vaccine) and SD-IIV will be evaluated for outcomes including all polymerase chain reaction (PCR)-confirmed influenza, PCR-confirmed hospitalized influenza, hospitalized community-acquired pneumonia and cardio-respiratory events.

Study Overview

• Status: Completed
• Conditions: Stroke; Pneumonia; Influenza; Congestive Heart Failure; Acute Myocardial Infarction; Lower Respiratory Tract Infection
• Intervention / Treatment: Biological: Flublok Quadrivalent; Biological: Standard Dose Inactivated Influenza Vaccine (SD-IIV)

• Study Type: Observational
• Enrollment (Actual): 2776278

Contacts and Locations

Study Locations

• United States
  • California
    • Oakland, California, United States, 94612
      • Kaiser Permanente Northern California (entire region)

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 64 years (Adult)
• Accepts Healthy Volunteers: Yes

• Sampling Method: Probability Sample

Study Population

Eligible adults aged 18-64 years will receive either Flublok Quadrivalent vaccine or a standard dose inactivated influenza vaccine in the course of routine influenza vaccination during each of the two influenza seasons of the study period at Kaiser Permanente Northern California.

Description

Inclusion Criteria:

• Between the ages of ≥18 and <65 years at the time of influenza vaccination
• Receive either Flublok Quadrivalent vaccine or standard dose inactivated influenza vaccine at a Kaiser Permanente Northern California facility during the study period from August 2018 through April 2020

Exclusion Criteria:

• Children <18 years old
• Adults ≥65 years old

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Prospective

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Flublok Recipients; Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine.	Biological: Flublok Quadrivalent; Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
SD-IIV Recipients; Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV).	Biological: Standard Dose Inactivated Influenza Vaccine (SD-IIV); For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Adults 50-64 Years Old With Polymerase-chain Reaction (PCR) Confirmed Influenza Tests	Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had a PCR-confirmed positive influenza test (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).	Up to 8 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Adults 50-64 Years Old Hospitalized With PCR-confirmed Influenza	Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had an inpatient stay and had a PCR-confirmed positive influenza test (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).	Up to 8 months
Number of Adults 50-64 Years Old Hospitalized With Community-acquired Pneumonia	Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had an inpatient stay for community-acquired pneumonia (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).	Up to 8 months
Number of Adults 50-64 Years Old Hospitalized With Cardio-respiratory Events	Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had an inpatient stay for cardio-respiratory events (e.g., pneumonia, other lower respiratory infections, acute myocardial infarction, congestive heart failure, stroke) (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).	Up to 8 months
Number of Adults 50-64 Years Old With Polymerase-chain Reaction (PCR) Confirmed Influenza A Tests	Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had a PCR-confirmed positive influenza A test (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).	Up to 8 months
Number of Adults 50-64 Years Old With Polymerase-chain Reaction (PCR) Confirmed Influenza B Tests	Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had a PCR-confirmed positive influenza B test (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).	Up to 8 months

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Adults 18-49 Years Old Hospitalized With Community-acquired Pneumonia	Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had an inpatient stay for community-acquired pneumonia (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).	Up to 8 months
Number of Adults 50-64 Years Old With Influenza-Like Illness (ILI)	Patients who receive either Flublok or SD-IIV will be retroactively assessed (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30) for influenza-like illness (ILI) International Classification of Diseases, 10th Edition (and absence of a negative lab-confirmed influenza)	Up to 8 months
Number of Adults 50-64 Years Old With All-Cause-Hospitalizations	Patients who receive either Flublok or SD-IIV will be retroactively assessed (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30) for all-cause hospitalizations	Up to 8 months
Number of Adults 50-64 Years Old With All-Cause Mortality	Patients who receive either Flublok or SD-IIV will be retroactively assessed (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30) for all-cause mortality	Up to 8 months
Number of Adults 18-49 Years Old With Polymerase-chain Reaction (PCR) Confirmed Influenza Tests	Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had a PCR-confirmed positive influenza test (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).	Up to 8 months
Number of Adults 18-49 Years Old Hospitalized With PCR-confirmed Influenza	Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had an inpatient stay and had a PCR-confirmed positive influenza test (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).	Up to 8 months
Number of Adults 18-49 Years Old Hospitalized With Cardio-respiratory Events	Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had an inpatient stay for cardio-respiratory events (e.g., pneumonia, other lower respiratory infections, acute myocardial infarction, congestive heart failure, stroke) (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).	Up to 8 months
Number of Adults 18-49 Years Old With Influenza-Like Illness (ILI)	Patients who receive either Flublok or SD-IIV will be retroactively assessed (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30) for influenza-like illness (ILI) International Classification of Diseases, 10th Edition (and absence of a negative lab-confirmed influenza)	Up to 8 months
Number of Adults 18-49 Years Old With All-Cause-Hospitalizations	Patients who receive either Flublok or SD-IIV will be retroactively assessed (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30) for all-cause hospitalizations	Up to 8 months
Number of Adults 18-49 Years Old With All-Cause Mortality	Patients who receive either Flublok or SD-IIV will be retroactively assessed (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30) for all-cause mortality	Up to 8 months
Number of Adults 18-49 Years Old With Polymerase-chain Reaction (PCR) Confirmed Influenza A Tests	Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had a PCR-confirmed positive influenza A test (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).	Up to 8 months
Number of Adults 18-49 Years Old With Polymerase-chain Reaction (PCR) Confirmed Influenza B Tests	Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had a PCR-confirmed positive influenza B test (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).	Up to 8 months

Collaborators and Investigators

• Sponsor: Kaiser Permanente
• Collaborators: Sanofi Pasteur, a Sanofi Company
• Investigators: Principal Investigator: Nicola P Klein, MD, PhD, Kaiser Permanente

Publications and helpful links

General Publications

• Hsiao A, Hansen J, Nunley KV, Lewis N, Selmani A, Inamdar A, Mallett-Moore T, Izikson R, Rudin D, Klein NP. Safety of recombinant quadrivalent influenza vaccine compared to inactivated influenza vaccine in Chinese adults: An observational study. Vaccine. 2022 Jan 31;40(5):774-779. doi: 10.1016/j.vaccine.2021.12.035. Epub 2022 Jan 6.

Study record dates

Study Major Dates

• Study Start (Actual): September 16, 2018
• Primary Completion (Actual): April 9, 2021
• Study Completion (Actual): December 31, 2022

Study Registration Dates

• First Submitted: September 27, 2018
• First Submitted That Met QC Criteria: October 1, 2018
• First Posted (Actual): October 3, 2018

Study Record Updates

• Last Update Posted (Actual): April 8, 2025
• Last Update Submitted That Met QC Criteria: March 20, 2025
• Last Verified: March 1, 2025

More Information

Terms related to this study

• Keywords: influenza; vaccine effectiveness
• Additional Relevant MeSH Terms: Vascular Diseases; Cardiovascular Diseases; Pathologic Processes; Heart Diseases; Infections; Orthomyxoviridae Infections; RNA Virus Infections; Virus Diseases; Respiratory Tract Diseases; Necrosis; Myocardial Ischemia; Ischemia; Heart Failure; Influenza, Human; Respiratory Tract Infections; Myocardial Infarction; Infarction
• Other Study ID Numbers: CN-18-3176

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: All data reported to Sanofi Pasteur by the Kaiser Permanente Northern California Vaccine Study Center will be deidentified and aggregated.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No