Browsing by Author "Al-Kuwari, Mohamed Ghaith"

Now showing items 1-20 of 37

    • Addressing bias in the definition of SARS-CoV-2 reinfection: implications for underestimation 

      Chemaitelly, Hiam; Ayoub, Houssein H.; Tang, Patrick; Yassine, Hadi M.; Al Thani, Asmaa A.; ... more authors ( 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. 

      Chemaitelly, Hiam; Ayoub, Houssein H; Coyle, Peter; Tang, Patrick; Hasan, Mohammad R; ... more authors ( 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 

      Al-Abdulla, S.A.; Haj Bakri, Ahmad; Mansaray, Mariama Aminata; Al-Kuwari, Mohamed Ghaith ( 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 

      Chemaitelly, Hiam; Ayoub, Houssein H.; Coyle, Peter; Tang, Patrick; Yassine, Hadi M.; ... more authors ( 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 

      Chemaitelly, Hiam; Ayoub, Houssein H; Coyle, Peter; Tang, Patrick; Hasan, Mohammad R; ... more authors ( 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 

      Hiam, Chemaitelly; Ayoub, Houssein H.; Coyle, Peter; Tang, Patrick; Hasan, Mohammad R.; ... more authors ( 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 

      Al-Kuwari, Mohamed Ghaith; Mohammed, Azza Mustafa; Abdulmajeed, Jazeel; Al-Romaihi, Hamad; Al-Mass, Maryam; ... more authors ( 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 

      Chemaitelly, Hiam; Ayoub, Houssein H.; Coyle, Peter; Tang, Patrick; Hasan, Mohammad R.; ... more authors ( 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 

      Bansal, Devendra; Abdulmajeed, Jazeel; Al-Shamali, Maha H.M.A.; Albayat, Soha S.A.; Himatt, Sayed M.; ... more authors ( 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. 

      Chemaitelly, Hiam; Nagelkerke, Nico; Ayoub, Houssein H; Coyle, Peter; Tang, Patrick; ... more authors ( 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. 

      Chemaitelly, Hiam; Ayoub, Houssein H; AlMukdad, Sawsan; Coyle, Peter; Tang, Patrick; ... more authors ( 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 

      Sukik, Layan; Chemaitelly, Hiam; Ayoub, Houssein H.; Coyle, Peter; Tang, Patrick; ... more authors ( 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 

      Chemaitelly, Hiam; Ayoub, Houssein H.; Coyle, Peter; Tang, Patrick; Hasan, Mohammad R.; ... more authors ( 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 

      Layan, Sukik; Chemaitelly, Hiam; Ayoub, Houssein H.; Coyle, Peter; Tang, Patrick; ... more authors ( 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. 

      Qassim, Suelen H; Chemaitelly, Hiam; Ayoub, Houssein H; AlMukdad, Sawsan; Tang, Patrick; ... more authors ( 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 

      Heba N., Altarawneh; Chemaitelly, Hiam; Ayoub, Houssein H.; Tang, Patrick; Hasan, Mohammad R.; ... more authors ( 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 

      Qassim, Suelen H.; Hasan, Mohammad R.; Tang, Patrick; Chemaitelly, Hiam; Ayoub, Houssein H.; ... more authors ( 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 

      Ayoub, Houssein H.; Chemaitelly, Hiam; Tang, Patrick; Hasan, Mohammad R.; Yassine, Hadi M.; ... more authors ( 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. 

      Sukik, Layan; Chemaitelly, Hiam; Ayoub, Houssein H; Coyle, Peter; Tang, Patrick; ... more authors ( 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 ...

    • History of primary-series and booster vaccination and protection against Omicron reinfection 

      Chemaitelly, Hiam; Ayoub, Houssein H.; Tang, Patrick; Coyle, Peter V.; Yassine, Hadi M.; ... more authors ( American Association for the Advancement of Science , 2023 , Article)
      Laboratory evidence suggests a possibility of immune imprinting for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We investigated the differences in the incidence of SARS-CoV-2 reinfection in a ...