VE and the rates of (A) RT-PCR‒confirmed SARS-CoV-2 Infection and (B) the composite severe COVID-19 outcome (hospitalization + ICU admission + death) among vaccinated and unvaccinated as well as (C) a comparison of these rates between vaccinated without or with booster in the last quarter of 2021.
Note: Overall vaccine effectiveness is based on the latest quarter in which a patient was tested (Q1: n=39,782; Q2: n=36,058, Q3: n=34,697, Q4: n=41,525; shown in the Methods section). + denotes logistic regression. Adjustment 1: age, gender, race/ethnicity. Adjustment 5: Adjustment 1 + Elixhauser score AHRQ + Persons per square mile + neighborhood disadvantage index + past COVID-19 infection + healthcare worker status.
AHRQ, Agency for Healthcare Research and Quality; ICU, intensive care unit; Q, quarter; RT-PCR, reverse transcription-polymerase chain reaction; VE, vaccine effectiveness.