Browsing by Author "Al-Kuwari, Mohamed Ghaith"
Now showing items 1-20 of 39
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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 ... -
Assessing the impact of annual health screenings in identifying noncommunicable disease risk factors within Qatar’s primary health care corporation Qatari registered population
( Frontiers Media SA , 2024 , Article)Background: Noncommunicable diseases (NCDs) are a significant global health burden, including in Qatar, where cardiovascular diseases cause mortality. This study examines the outcomes of the annual health checkup implemented ... -
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 ... -
Comparative effectiveness of one versus two doses of COVID-19 vaccines in Qatar: Evidence of converging protection over time
( Elsevier , 2025 , Article)BackgroundSupply constraints during the coronavirus disease 2019 (COVID-19) pandemic led to vaccination strategies that prioritized first-dose coverage. To evaluate the merit of this approach, this study compared the ... -
COVID-19 testing, incidence, and positivity trends among school age children during the academic years 2020-2022 in the State of Qatar: special focus on using CDC indicators for community transmission to evaluate school attendance policies and public health response
( BioMed Central Ltd , 2024 , Article)Background There exists a gap in our understanding of the age-dependent epidemiological dynamics of SARS-CoV-2 among school-age children in comparison to adults within the State of Qatar. Additionally, there has been ... -
Differential protection against SARS-CoV-2 reinfection pre- and post-Omicron
( Springer Nature , 2025 , Article)The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly evolved over short timescales, leading to the emergence of more transmissible variants such as Alpha and Delta1, 2–3. The arrival of the Omicron ... -
Duration of COVID-19 mRNA Vaccine Effectiveness against Severe Disease
( MDPI , 2022 , Article)Waning immunity following administration of mRNA-based COVID-19 vaccines remains a concern for many health systems. We undertook a study to determine if recent reports of waning for severe disease could have been attributed ... -
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 ... -
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, 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 SARS-CoV-2 infection incidence and detection rates: Demonstrating a novel surveillance method
( Elsevier , 2025 , Article)ObjectivesAssessing the cumulative incidence of infection conventionally relies on documented infections or serological surveys, both of which have limitations. This study introduces a novel and practical method leveraging ... -
Evaluating Hospital Admission Data as Indicators of COVID-19 Severity: A National Assessment in Qatar.
( Oxford University Press , 2025 , Article)Accurately assessing SARS-CoV-2 infection severity is essential for understanding the health impact of the infection and evaluating the effectiveness of interventions. This study investigated whether SARS-CoV-2-associated ... -
Evaluating the cost-effectiveness of COVID-19 mRNA primary-series vaccination in Qatar: An integrated epidemiological and economic analysis
( PLoS One , 2025 , Article)Qatar implemented a mass primary-series vaccination campaign to mitigate the impact of the coronavirus disease 2019 (COVID-19) pandemic. This study aimed to retrospectively evaluate the cost-effectiveness of this program ...
