Seroprevalence surveys suggest that more than a third and possibly more than half of the
global population has been infected with SARS-CoV-2 by early 2022. As large numbers of …

Protection against Omicron by Previous SARS-CoV-2 Infection Using a national Covid-19
database in Qatar, investigators found that previous SARS-CoV-2 infection provided …

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

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 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 …

Abstract SARS-CoV-2 wastewater-based surveillance (WBS) offers a tool for cost-effective
oversight of a population's infections. In the past two years, WBS has proven to be crucial for …

Background The level of protection after a SARS-CoV-2 infection against reinfection and
COVID-19 disease remains important with much of the world still unvaccinated. Methods …

Qatar experienced a large severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)
Omicron (B. 1.1. 529) wave that started on 19 December 2021 and peaked in mid-January …

There is significant genetic distance between SARS-CoV-2 Omicron (B. 1.1. 529) variant BA.
1 and BA. 2 sub-lineages. This study investigates immune protection of infection with one …

Dear Editor, SARS-CoV-2 Omicron variant BA. 1 first emerged on the Chinese mainland on
January 8, 2022, in Tianjin and caused a large wave of infections. 1 Four rounds of mass …