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 …

Background Understanding the level and characteristics of protection from past SARS-CoV-
2 infection against subsequent re-infection, symptomatic COVID-19 disease, and severe …

Abstract The SARS-CoV-2 Omicron variant has demonstrated enhanced transmissibility and
escape of vaccine-derived immunity. Although first-generation vaccines remain effective …

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) breakthrough infections in
vaccinated individuals and reinfections in previously infected individuals have become …

Nirmatrelvir, an oral antiviral targeting the 3CL protease of SARS-CoV-2, has been
demonstrated to be clinically useful against COVID-19 (refs.,). However, because SARS …

Covid-19 Vaccines — Immunity, Variants, Boosters | New England Journal of Medicine Skip to
main content The New England Journal of Medicine homepage Advanced Search SEARCH …

Protective Effect of Previous SARS-CoV-2 Infection against Omicron BA.4 and BA.5 Subvariants |
New England Journal of Medicine Skip to main content The New England Journal of Medicine …

Studies have reported reduced natural SARS-CoV-2 infection-and vaccine-induced
neutralization against omicron BA. 4/BA. 5 compared with earlier omicron subvariants. This …

Immune Imprinting and Protection against Repeat Reinfection with SARS-CoV-2 | New England
Journal of Medicine Skip to main content The New England Journal of Medicine homepage …

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 …