Importance A correlation between antibody levels and risk of infection has been
demonstrated for the wild-type, Alpha, and Delta SARS-COV-2 variants. High rates of …

Objective: To study SARS-CoV-2 reinfections in health-care workers (HCWs) of the
University Health Agency Giuliano-Isontina (ASUGI), covering the provinces of Trieste and …

As the COVID-19 pandemic continues, long-term immunity against SARS-CoV-2 will be
important globally. Official weekly cases have not dropped below 2 million since September …

Evidence on the effectiveness of COVID-19 vaccines among people who recovered from a
previous SARS-CoV-2 infection is warranted to inform vaccination recommendations. Using …

Background Although most children and adolescents have had a previous SARS-CoV-2
infection and many continue to receive COVID-19 vaccinations, studies of the effectiveness …

Test-negative designs (TNDs) are used to assess vaccine effectiveness (VE). Protection
from infection-induced immunity may confound the association between case and …

Third doses of COVID-19 vaccines were widely deployed following the primary vaccine
course waning and the emergence of the Omicron-variant. We investigated protection from …

Abstracts Objectives To assess the dynamics of the anti-SARS-CoV-2 IgG antibody levels
and their efficacy against COVID-19. Methods We conducted a longitudinal serological …

This report examines the evolving role of coronavirus disease 2019 (COVID-19) vaccination
in Japan, especially in light of the reduced public concern following the reclassification of …

The immune effector mechanisms involved in protecting against severe COVID-19 infection
in elderly nursing home residents following vaccination or natural infection are not well …