In late 2020, after circulating for almost a year in the human population, severe acute
respiratory syndrome coronavirus 2 (SARS-CoV-2) exhibited a major step change in its …

Importance Estimates of the rate of waning of vaccine effectiveness (VE) against COVID-19
are key to assess population levels of protection and future needs for booster doses to face …

Background Synthesising evidence on the long-term vaccine effectiveness of COVID-19
vaccines (BNT162b2 [Pfizer–BioNTech], mRNA-1273 [Moderna], ChAdOx1 nCoV-19 …

The Omicron variant has been associated with reduced vaccine effectiveness (VE) against
mild disease with rapid waning. Meanwhile Omicron has also been associated with milder …

Since the onset of the coronavirus disease 2019 (COVID-19) pandemic, multiple severe
acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with increasing ability to …

Background There is an urgent public health need to evaluate disease severity in adults
hospitalised with Delta and Omicron SARS-CoV-2 variant infections. However, limited data …

Effectiveness of 2, 3, and 4 COVID-19 mRNA Vaccine Doses Among Immunocompetent Adults
During Periods when SARS-CoV-2 Omicron BA.1 and BA.2/BA.2.12.1 Sublineages …

Given the emergence of the SARS-CoV-2 Omicron BA. 1 and BA. 2 variants and the roll-out
of booster COVID-19 vaccination, evidence is needed on protection conferred by primary …

Since the start of the COVID-19 pandemic, numerous variants of SARS-CoV-2 have been
reported worldwide. The advent of variants of concern (VOCs) raises severe concerns amid …

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 …