Pfizer-BioNTech COVID-19 BNT162b2 Vaccine Effectiveness Study – Kaiser Permanente Southern California

Overview

The primary objective of this study is to determine the vaccine effectiveness of 2 doses of Pfizer-BioNTech BNT162b2 vaccine against COVID-19-associated hospitalization. There will be a large retrospective database study using two parallel study designs: a test-negative case-control design and a retrospective cohort design. Exploratory analyses of VE estimates by strain type will be conducted.

Full Title of Study: “Pfizer-BioNTech COVID-19 BNT162b2 Vaccine Effectiveness Study – Kaiser Per-manente Southern California”

Study Type

  • Study Type: Observational
  • Study Design
    • Time Perspective: Retrospective
  • Study Primary Completion Date: April 1, 2022

Detailed Description

The primary objective of this study is to determine the vaccine effectiveness (VE) of 2-doses of Pfizer's BNT162b2 vaccine against COVID-19-associated hospitalization. In addition, VE of 1 dose and at least one dose will be determined. Other outcomes in addition to hospitalization to be assessed include COVID-19-associated ED admissions, ICU admissions, outpatient visits and death. To assess VE, we propose a large retrospective database study using two parallel study designs: a test-negative case-control design and a retrospective cohort design. The test-negative design (TND) will assess VE against COVID-19 hospitalization (primary endpoint) and emergency department (ED) admission. The retrospective cohort analysis will assess VE against COVID-19 hospitalization (primary), ICU admission, death, ED admission, and outpatient disease (with no subsequent hospitalization within 14 days). We will further conduct exploratory analyses of VE estimates by strain type.

Interventions

  • Biological: Primary Exposure Status of Pfizer-BioNTech COVID-19 Vaccine
    • Pfizer-BioNTech COVID-19 vaccine

Arms, Groups and Cohorts

  • Fully vaccinated
    • 2 doses of BNT162b2 received with ≥7 days between receipt of the 2nd dose and the index date. This group will serve as the ‘exposed’ group evaluated in the primary objective.
  • Partially vaccinated
    • 1 dose (only) of BNT162b2 received with ≥14 days between receipt of the 1st dose and the index date.
  • Ever vaccinated
    • ≥1 dose of BNT162b2 received with ≥14 days between index date and receipt of the 1st dose
  • Never vaccinated
    • never received BNT162b2. This group will serve as the reference exposure group (i.e., ‘unexposed’ group) in all VE analyses

Clinical Trial Outcome Measures

Primary Measures

  • The effectiveness of 2 doses of BNT162b2 (i.e., fully vaccinated) against hospitalization for ARI due to SARS-CoV-2 infection
    • Time Frame: Dec 2020-Apr 2022
    • VE calculated as 1 minus the odds ratio (OR) comparing the odds of being fully vaccinated (2 doses) with BNT162b2 for hospitalized cases and controls, multiplied by 100%.

Secondary Measures

  • The effectiveness of 2 doses of BNT162b2 (i.e., fully vaccinated) against ED admission (without subsequent hospitalization) for ARI due to SARS-CoV-2 infection.
    • Time Frame: Through study completion, average of one year
    • VE calculated as 1 minus the OR comparing the odds of being fully vaccinated (2 doses) with BNT162b2 for ED cases and controls, multiplied by 100%.
  • The effectiveness of only 1 dose of BNT162b2 (i.e., partially vaccinated) against hospitalization for ARI due to SARS-CoV-2 infection
    • Time Frame: Through study completion, average of one year
    • VE calculated as 1 minus the OR comparing the odds of being partially vaccinated with BNT162b2 (only 1 dose) for hospitalized cases and controls, multiplied by 100%.
  • The effectiveness of only 1 dose of BNT162b2 (i.e., partially vaccinated) against ED admission (without subsequent hospitalization) for ARI due to SARS-CoV-2 infection.
    • Time Frame: Through study completion, average of one year
    • VE calculated as 1 minus the OR comparing the odds of being partially vaccinated with BNT162b2 (only 1 dose) for ED cases and controls, multiplied by 100%.
  • The effectiveness of ≥1 dose of BNT162b2 (i.e., ever vaccinated) against hospitalization for ARI due to SARS-CoV-2 infection.
    • Time Frame: Through study completion, average of one year
    • VE calculated as 1 minus the OR comparing the odds of ever being vaccinated (≥1 dose) with BNT162b2 for hospitalized cases and controls, multiplied by 100%.
  • The effectiveness of ≥1 dose of BNT162b2 (i.e., ever vaccinated) against ED admission (without subsequent hospitalization) for ARI due to SARS-CoV-2 infection.
    • Time Frame: Through study completion, average of one year
    • VE calculated as 1 minus the OR comparing the odds of ever being vaccinated (≥1 dose) with BNT162b2 for ED cases and controls, multiplied by 100%.
  • The effectiveness of BNT162b2 against hospitalization and ED admission stratified by prevalent or important viral strains
    • Time Frame: Through study completion, average of one year
    • BNT162b2 VE estimates stratified by virus variant (as determined by genome sequencing) and select descriptive analyses described above
  • The effectiveness of BNT162b2 against severe hospitalization-related outcomes (e.g., ICU admission, mechanical ventilation, and death)
    • Time Frame: Through study completion, average of one year
    • BNT162b2 VE estimates against severe out-comes including ICU admission, mechanical ventilation, and death

Participating in This Clinical Trial

Inclusion Criteria Test Negative Design

  • KPSC patients 16 years or older who are admitted to the hospital (primary objective) with acute respiratory infection (ARI) after 14 December 2020 (date of first vaccinations at KPSC), and who receive a PCR test for SARS-CoV-2. – For secondary objectives estimating VE against ED admission, the TND will include KPSC patients 16 years or older who present to the ED with ARI after 14 December 2020, and who receive a PCR test for SARS-CoV-2. – Membership requirement of 6 months prior to index date, which is de-fined as the date of hospitalization or ED admission (allowing 31-day administrative gap), to facilitate accurate capture of comorbid conditions. Inclusion Criteria Cohort Design – All KPSC members as of 14 December 2020 (date of first Pfizer vaccination at KPSC) who are age 16 and older. – Patients must have at least 6 months of membership (allowing 31-day administrative gap) prior to 14 December 2020 (index date, date vaccinations first began at KPSC) to facilitate accurate capture of comorbid conditions. Exclusion Criteria Test Negative Design • Patients who receive any other newly licensed or investigational SARS-CoV-2 vaccine or COVID-19 prophylactic agent other than Pfizer's COVID-19 vaccine prior to hospitalization (or ED, for secondary objective) will be excluded from the analysis. Patients will also be excluded if the index date is within certain time windows from vaccination date. Exclusion Criteria Cohort Design • There will be no exclusion criteria for the cohort design, however patients will be censored for receiving any other newly licensed or investigational SARS-CoV-2 vaccine or COVID-19 prophylactic agent other than Pfizer's COVID-19 vaccine. Patients will also be censored if the event (hospitalization, ED encounter, etc.) occurs within certain time windows from vaccination date.

Gender Eligibility: All

Minimum Age: 16 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • Pfizer
  • Provider of Information About this Clinical Study
    • Sponsor
  • Overall Official(s)
    • Pfizer CT.gov Call Center, Study Director, Pfizer

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