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Clinical Trial Summary

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. VE estimates by various strata and strain type will be conducted.


Clinical Trial Description

The primary objective of the study is to estimate vaccine effectiveness (VE) of 2 doses of Pfizer's BNT162b2 vaccine against acute respiratory illness (ARI) requiring hospitalization due to SARS-CoV-2 infection among KPSC members eligible for vaccination. VE will be evaluated using a test-negative design (TND), including all KPSC patients eligible for vaccination who are admitted to the hospital with (ARI) after 14 December 2020 (date of first vaccinations at KPSC), and who receive a PCR test for SARS-CoV-2. Secondary and exploratory objectives may examine VE for 1 dose vaccination, at least 1 dose, >2 doses, monovalent, bivalent or mixed dosing schedules as well as against ED admission, specific variants, mixed dosing schedules, durability, age cut-offs to align with regulatory authorizations/approvals and other populations of interest. Additionally, we will estimate VE using a full cohort design, including all KPSC members eligible for vaccination. To assess VE, we propose a large retrospective database study using two parallel study de-signs: a test-negative case-control design and a retrospective cohort design. The TND will assess VE against COVID-19 hospitalization (primary endpoint) and ED admission. The retrospective cohort analysis may assess VE against COVID-19 hospitalization (primary), ICU admission, death, ED admission, and outpatient disease (with no subsequent hospitalization within 14 days). The BNT162b2 BA.4/BA.5 bivalent vaccine effectiveness will only be assessed via a test negative design due to the limitations regarding testing bias. As the pandemic evolved PCR-confirmed testing and reporting became less routine and differences in health care seeking behaviors were seen based on vaccination status. VE for the XBB1.5-adapted monovalent vaccine will be defined as receipt of Pfizer -BioNTech XBB1.5-adapted monovalent vaccine with greater than or equal to 14 days between receipt of vaccine and the event date. We will further conduct additional analyses of VE estimates by various patient characteristics and strain types. ;


Study Design


Related Conditions & MeSH terms


NCT number NCT04848584
Study type Observational
Source Pfizer
Contact Pfizer CT.gov Call Center
Phone 1-800-718-1021
Email ClinicalTrials.gov_Inquiries@pfizer.com
Status Recruiting
Phase
Start date May 15, 2021
Completion date June 15, 2025

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