Background The global surge in the omicron (B. 1.1. 529) variant has resulted in many
individuals with hybrid immunity (immunity developed through a combination of SARS-CoV …

Real-world data on the effectiveness of COVID-19 vaccines against the Omicron variant (B.
1.1. 529) is limited. This systematic review aimed to investigate the real-world effectiveness …

Background There is a paucity of data on vaccine-induced or infection-induced (hybrid or
natural) immunity against omicron (B. 1.1. 529) subvariant BA. 2, particularly in comparing …

Background: The evolving proportion of the population considered immunologically naive
versus primed for more efficient immune memory response to SARS-CoV-2 has implications …

Background A rapidly growing body was observed of literature evaluating the vaccine
effectiveness (VE) against Omicron in test-negative design studies. Methods We …

Background We aimed to systematically review the magnitude and duration of the protective
effectiveness of prior infection (PE) and hybrid immunity (HE) against Omicron infection and …

We investigated the design and analysis of observational booster vaccine effectiveness (VE)
studies by performing a scoping review of booster VE literature with a focus on study design …

Abstract Background Studies comparing SARS-CoV-2 reinfection outcomes among
individuals with previous infection (natural immunity) and previous infection plus vaccination …

Video Abstract BACKGROUND AND OBJECTIVES Understanding the real-world impact of
severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mitigation measures …

Purpose Despite the need to generate valid and reliable estimates of protection levels
against SARS-CoV-2 infection and severe course of COVID-19 for the German population in …