Importance The incidence of SARS-CoV-2 infection, including among individuals who have
received 2 doses of COVID-19 vaccine, increased substantially following the emergence of …

Importance Assessing COVID-19 vaccine performance against the rapidly spreading SARS-
CoV-2 Omicron variant is critical to inform public health guidance. Objective To estimate the …

Importance Few studies have evaluated the waning of vaccine effectiveness against severe
outcomes caused by SARS-CoV-2 Omicron infection. Hong Kong is providing inactivated …

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 …

The emergence of the Omicron variant (B. 1.1. 529) of SARS-CoV-2 has raised concerns
about how mutations in the spike protein might influence immune escape and vaccine …

Background A rapid increase in coronavirus disease 2019 (Covid-19) cases due to the
omicron (B. 1.1. 529) variant of severe acute respiratory syndrome coronavirus 2 in highly …

Vaccine effectiveness is lower and wanes faster against infection and symptomatic disease
caused by the omicron variant of SARS-CoV-2 than was observed with previous variants …

In 25 US jurisdictions, decreases in case incidence rate ratios for unvaccinated versus fully
vaccinated persons with and without booster vaccine doses were observed when the …

Among adults hospitalized with SARS-CoV-2 infection during Omicron predominance,
COVID-19 vaccination, including with a booster dose, was associated with lower likelihood …

Importance Recent SARS-CoV-2 Omicron variant sublineages, including BA. 4 and BA. 5,
may be associated with greater immune evasion and less protection against COVID-19 after …