Since commencement of COVID-19 pandemic, several SARS-CoV-2 variants have emerged
amid containment efforts via vaccination. The Delta variant (B. 1.617. 2), discovered in …

Abstract SARS-CoV-2 Omicron BA. 1 and BA. 2 subvariants are genetically divergent. We
conducted a matched, test-negative, case-control study to estimate duration of protection of …

Background Waning of vaccine protection against coronavirus disease 2019 (Covid-19) and
the emergence of the omicron (or B. 1.1. 529) variant of the severe acute respiratory …

Background Waning of vaccine protection against severe acute respiratory syndrome
coronavirus 2 (SARS-CoV-2) infection or coronavirus disease 2019 (Covid-19) is a concern …

Abstract Short Summary Severe acute respiratory syndrome coronavirus 2 infection from the
Omicron variant in children/adolescents is less severe than infection from the Delta variant …

Waning SARS-CoV-2 Immunity in Qatar The protection afforded by the mRNA-1273 vaccine
against SARS-CoV-2 infection in Qatar seemed to wane over several months after …

Background The future of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-
2) pandemic hinges on virus evolution and duration of immune protection of natural infection …

Importance The effect of prior SARS-CoV-2 infection on vaccine protection remains poorly
understood. Objective To assess protection from SARS-CoV-2 breakthrough infection after …

Importance The Delta variant is now the predominant circulating SARS-CoV-2 strain
worldwide. Severity of illness in persons infected with the SARS-CoV-2 Delta variant …

Summary BA. 2.86, a recently identified descendant of the severe acute respiratory
syndrome coronavirus 2 (SARS-CoV-2) Omicron BA. 2 sublineage, contains∼ 35 mutations …