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السجلات المعروضة 11 -- 20 من 31
Characterizing the effective reproduction number during the COVID-19 pandemic: Insights from Qatar’s experience
(
International Society of Global Health
, 2022 , Article)
Background: The effective reproduction number, Rt, is a tool to track and understand epidemic dynamics. This investigation of Rt estimations was conducted to guide the national COVID-19 response in Qatar, from the onset ...
Effects of BA.1/BA.2 subvariant, vaccination, and prior infection on infectiousness of SARS-CoV-2 omicron infections.
(
Oxford University Press
, 2022 , Article)
Compared to BA.1, BA.2 was associated with lower RT-qPCR cycle threshold (Ct) value-3.53 fewer cycles (95% CI: 3.46-3.60), signifying higher infectiousness. This may reflect higher viral load and/or longer duration of ...
Duration of mRNA vaccine protection against SARS-CoV-2 Omicron BA.1 and BA.2 subvariants in Qatar.
(
Nature Research
, 2022 , Article)
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 the second and third/booster doses of mRNA COVID-19 ...
Protection of Omicron sub-lineage infection against reinfection with another Omicron sub-lineage
(
Nature Research
, 2022 , Article)
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 sub-lineage against reinfection with the other ...
Effect of mRNA Vaccine Boosters against SARS-CoV-2 Omicron Infection in Qatar.
(
Massachusetts Medical Society
, 2022 , Article)
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 syndrome coronavirus 2 (SARS-CoV-2) have led to expedited ...
Relative infectiousness of SARS-CoV-2 vaccine breakthrough infections, reinfections, and primary infections.
(
Springer
, 2022 , Article)
SARS-CoV-2 breakthrough infections in vaccinated individuals and in those who had a prior infection have been observed globally, but the transmission potential of these infections is unknown. The RT-qPCR cycle threshold ...
Effects of Previous Infection and Vaccination on Symptomatic Omicron Infections.
(
Massachusetts Medical Society
, 2022 , Article)
The protection conferred by natural immunity, vaccination, and both against symptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection with the BA.1 or BA.2 sublineages of the omicron (B.1.1.529) ...
SARS-CoV-2 antibody-positivity protects against reinfection for at least seven months with 95% efficacy
(
Elsevier
, 2021 , Article)
Background Reinfection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been documented, raising public health concerns. SARS-CoV-2 reinfections were assessed in a cohort of antibody-positive persons ...
COVID-19 risk score as a public health tool to guide targeted testing: A demonstration study in Qatar
(
Public Library of Science
, 2022 , Article)
We developed a Coronavirus Disease 2019 (COVID-19) risk score to guide targeted RTPCR testing in Qatar. The Qatar national COVID-19 testing database, encompassing a total of 2,688,232 RT-PCR tests conducted between February ...
Effects of SARS-CoV-2 Alpha, Beta, and Delta variants, age, vaccination, and prior infection on infectiousness of SARS-CoV-2 infections
(
Frontiers Media
, 2022 , Article)
In 2021, Qatar experienced considerable incidence of SARS-CoV-2 infection that was dominated sequentially by the Alpha, Beta, and Delta variants. Using the cycle threshold (Ct) value of an RT-qPCR-positive test to proxy ...