• 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 ...
    • 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 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 ...
    • 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 ...
    • Long-term COVID-19 booster effectiveness by infection history and clinical vulnerability and immune imprinting: a retrospective population-based cohort study 

      Hiam, Chemaitelly; Ayoub, Houssein H; Tang, Patrick; Coyle, Peter; Yassine, Hadi M; ... more authors ( Elsevier , 2023 , Article)
      BackgroundLong-term effectiveness of COVID-19 mRNA boosters in populations with different previous infection histories and clinical vulnerability profiles is inadequately understood. We aimed to investigate the effectiveness ...
    • Population immunity of natural infection, primary-series vaccination, and booster vaccination in Qatar during the COVID-19 pandemic: an observational study 

      Suelen H., Qassim; Chemaitelly, Hiam; Ayoub, Houssein H.; Coyle, Peter; Tang, Patrick; ... more authors ( Elsevier , 2023 , Article)
      BackgroundWaning of natural infection protection and vaccine protection highlight the need to evaluate changes in population immunity over time. Population immunity of previous SARS-CoV-2 infection or of COVID-19 vaccination ...
    • Protection from previous natural infection compared with mRNA vaccination against SARS-CoV-2 infection and severe COVID-19 in Qatar: a retrospective cohort study 

      Hiam, Chemaitelly; Ayoub, Houssein H; AlMukdad, Sawsan; Coyle, Peter; Tang, Patrick; ... more authors ( Elsevier , 2022 , Article)
      BackgroundUnderstanding protection conferred by natural SARS-CoV-2 infection versus COVID-19 vaccination is important for informing vaccine mandate decisions. We compared protection conferred by natural infection versus ...
    • Protection of Omicron sub-lineage infection against reinfection with another Omicron sub-lineage 

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