Abstract Coronavirus Disease 2019 (COVID-19) has been the most severe public health
challenge in this century. Two years after its emergence, the rapid development and …

Background Vaccination, one of the most important and effective ways of preventing
infectious diseases, has recently been used to control the COVID-19 pandemic. The present …

Summary Background The SARS-CoV-2 delta (B. 1.617. 2) variant is highly transmissible
and spreading globally, including in populations with high vaccination rates. We aimed to …

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 …

Background Vaccine effectiveness against COVID-19 beyond 6 months remains
incompletely understood. We aimed to investigate the effectiveness of COVID-19 …

Background There are limited data on the effectiveness of the vaccines against symptomatic
coronavirus disease 2019 (Covid-19) currently authorized in the United States with respect …

Background Real-world evidence supporting vaccination against COVID-19 in individuals
who have recovered from a previous SARS-CoV-2 infection is sparse. We aimed to …

Background It was urgent and necessary to synthesize the evidence for vaccine
effectiveness (VE) against SARS-CoV-2 variants of concern (VOC). We conducted a …

Background: Between February and June 2021, the initial wild-type strains of SARS-CoV-2
were supplanted in Ontario, Canada, by new variants of concern (VOCs), first those with the …

The effectiveness of the BNT162b2 and ChAdOx1 vaccines against new severe acute
respiratory syndrome coronavirus 2 (SARS-CoV-2) infections requires continuous re …