تصفح Biomedical Research Center Research حسب المؤلف "Hasan, Mohammad R."
السجلات المعروضة 1 -- 20 من 34
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Addressing bias in the definition of SARS-CoV-2 reinfection: implications for underestimation
( Frontiers Media , 2024 , Article)Introduction: Reinfections are increasingly becoming a feature in the epidemiology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, accurately defining reinfection poses methodological ... -
Assessing healthy vaccinee effect in COVID-19 vaccine effectiveness studies: a national cohort study in Qatar.
( National Center for Biotechnology Information , 2025 , Article)This study investigated the presence of the healthy vaccinee effect-the imbalance in health status between vaccinated and unvaccinated individuals-in two rigorously conducted COVID-19 vaccine effectiveness studies involving ... -
Association of Prior SARS-CoV-2 Infection With Risk of Breakthrough Infection Following mRNA Vaccination in Qatar.
( American Medical Association , 2021 , Article)The effect of prior SARS-CoV-2 infection on vaccine protection remains poorly understood. To assess protection from SARS-CoV-2 breakthrough infection after mRNA vaccination among persons with vs without prior SARS-CoV-2 ... -
BNT162b2 and mRNA-1273 COVID-19 vaccine effectiveness against the SARS-CoV-2 Delta variant in Qatar.
( Nature Researc , 2021 , Article)With the global expansion of the highly transmissible SARS-CoV-2 Delta (B.1.617.2) variant, we conducted a matched test-negative case-control study to assess the real-world effectiveness of COVID-19 messenger RNA vaccines ... -
BNT162b2 antigen dose and SARS-CoV-2 omicron infection in adolescents
( Elsevier , 2023 , Other)COVID-19 vaccine antigen dose might affect protection against SARS-CoV-2 infection,1, 2 but direct evidence to quantify this effect is absent. We conducted a matched, retrospective, cohort study using a regression ... -
BNT162b2 Versus mRNA-1273 Vaccines: Comparative Analysis of Long-Term Protection Against SARS-CoV-2 Infection and Severe COVID-19 in Qatar
( Wiley , 2024 , Article)Background: This study provides a head-to-head comparison of the protection provided by the BNT162b2 and mRNA-1273 vaccines against SARS-CoV-2 infection and against severe COVID-19, covering primary series and third ... -
Characterizing the effective reproduction number during the COVID-19 pandemic: Insights from Qatar's experience
( Edinburgh University Global Health Society , 2022 , Article)Background The effective reproduction number, Rt, is a tool to track and understand pandemic dynamics. This investigation of Rt estimations was conducted to guide the national COVID-19 response in Qatar, from the onset of ... -
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 ... -
Distinct antibody repertoires against endemic human coronaviruses in children and adults.
( American Society for Clinical Investigation , 2021 , Article)Four endemic human coronaviruses (HCoVs) are commonly associated with acute respiratory infection in humans. B cell responses to these "common cold" viruses remain incompletely understood. Here we report a comprehensive ... -
Duration of immune protection of SARS-CoV-2 natural infection against reinfection.
( Oxford University Press , 2022 , Article)The future of the SARS-CoV-2 pandemic hinges on virus evolution and duration of immune protection of natural infection against reinfection. We investigated duration of protection afforded by natural infection, the effect ... -
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 ... -
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 ... -
Effectiveness and durability of a fourth dose of ancestral-strain mRNA vaccines against SARS-CoV-2 infection: a nationwide matched cohort study in Qatar
( Nature Research , 2025 , Article)Concerns about waning immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the emergence of new variants underscore the need for booster doses. Using a matched cohort design, this ... -
Effectiveness of ChAdOx1 nCoV-19 (Vaxzevria) primary series vaccine against SARS-CoV-2 beta and delta variants: a nationwide study
( Springer Nature , 2025 , Article)Background: This study assessed the real-world effectiveness of the ChAdOx1 nCoV-19 vaccine in adults against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, symptomatic infection, and severe ... -
Effectiveness of two and three doses of COVID-19 mRNA vaccines against infection, symptoms, and severity in the pre-omicron era: A time-dependent gradient
( Elsevier , 2024 , Article)BackgroundVaccines were developed and deployed to combat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. This study aimed to characterize patterns in the protection provided by the BNT162b2 and ... -
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 ... -
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) ... -
Effects of previous infection, vaccination, and hybrid immunity against symptomatic Alpha, Beta, and Delta SARS-CoV-2 infections: an observational study
( Elsevier , 2023 , Article)BackgroundProtection against SARS-CoV-2 symptomatic infection and severe COVID-19 of previous infection, mRNA two-dose vaccination, mRNA three-dose vaccination, and hybrid immunity of previous infection and vaccination ... -
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 ... -
Estimating protection afforded by prior infection in preventing reinfection: Applying the test-negative study design.
( Oxford University Press , 2023 , Article)The COVID-19 pandemic has highlighted the need to use infection testing databases to rapidly estimate effectiveness of prior infection in preventing reinfection ($P{E}_S$) by novel SARS-CoV-2 variants. Mathematical modeling ...
