• Assessment of the Risk of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Reinfection in an Intense Reexposure Setting 

      Abu-Raddad, Laith J.; Chemaitelly, Hiam; Malek, Joel A.; Ahmed, Ayeda A.; Mohamoud, Yasmin A.; ... more authors ( NLM (Medline) , 2021 , Article)
      BACKGROUND: Risk of reinfection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is unknown. We assessed the risk and incidence rate of documented SARS-CoV-2 reinfection in a cohort of laboratory-confirmed ...
    • Association of Prior SARS-CoV-2 Infection With Risk of Breakthrough Infection Following mRNA Vaccination in Qatar. 

      Abu-Raddad, Laith J; Chemaitelly, Hiam; Ayoub, Houssein H; Yassine, Hadi M; Benslimane, Fatiha M; ... more authors ( 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 ...
    • Bivalent mRNA-1273.214 vaccine effectiveness against SARS-CoV-2 omicron XBB* infections 

      Chemaitelly, Hiam; Ayoub, Houssein H.; AlMukdad, Sawsan; Faust, Jeremy S.; Tang, Patrick; ... more authors (2023 , Article)
      In October of 2022, Qatar introduced COVID-19 bivalent vaccination for persons ≥ 12 years using the 50-μg mRNA-1273.214 vaccine combining SARS-CoV-2 ancestral and omicron BA.1 strains.1 We estimated this vaccine’s effectiveness ...
    • BNT162b2 and mRNA-1273 COVID-19 vaccine effectiveness against the SARS-CoV-2 Delta variant in Qatar. 

      Tang, Patrick; Hasan, Mohammad R; Chemaitelly, Hiam; Yassine, Hadi M; Benslimane, Fatiha M; ... more authors ( 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 ...
    • Characterizing the effective reproduction number during the COVID-19 pandemic: Insights from Qatar’s experience 

      Bsat, Raghid; Chemaitelly, Hiam; Coyle, Peter; Tang, Patrick; Hasan, Mohammad R; ... more authors ( 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 ...
    • Characterizing the Qatar advanced-phase SARS-CoV-2 epidemic 

      Abu-Raddad, Laith J.; Chemaitelly, Hiam; Ayoub, Houssein H.; Al Kanaani, Zaina; Al Khal, Abdullatif; ... more authors ( springer nature , 2021 , Article)
      The overarching objective of this study was to provide the descriptive epidemiology of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic in Qatar by addressing specific research questions through a ...
    • Coronavirus Disease 2019 Disease Severity in Children Infected With the Omicron Variant 

      Butt, A.A.; Butt, Adeel A.; Dargham, Soha R.; Loka, Srusvin; Shaik, Riyazuddin M.; ... more authors ( NLM (Medline) , 2022 , Article)
      SHORT SUMMARY: Severe acute respiratory syndrome coronavirus 2 infection from the Omicron variant in children/adolescents is less severe than infection from the Delta variant. Those 6 to <18 years also have less severe ...
    • COVID-19 Disease Severity in Persons Infected with Omicron BA.1 and BA.2 Sublineages and Association with Vaccination Status 

      Butt, Adeel A.; Dargham, Soha R.; Coyle, Peter; Yassine, Hadi M.; Al-Khal, Abdullatif; ... more authors ( American Medical Association , 2022 , Other)
      [No abstract available]
    • Covid-19 Vaccine Protection among Children and Adolescents in Qatar. 

      Chemaitelly, Hiam; AlMukdad, Sawsan; Ayoub, Houssein H; Altarawneh, Heba N; Coyle, Peter; ... more authors ( Massachusetts Medical Society , 2022 , Article)
      The BNT162b2 vaccine against coronavirus disease 2019 (Covid-19) has been authorized for use in children 5 to 11 years of age and adolescents 12 to 17 years of age but in different antigen doses. We assessed the real-world ...
    • 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 ...
    • Effect of mRNA Vaccine Boosters against SARS-CoV-2 Omicron Infection in Qatar. 

      Abu-Raddad, Laith J; Chemaitelly, Hiam; Ayoub, Houssein H; AlMukdad, Sawsan; Yassine, Hadi M; ... more authors ( 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 of the BNT162b2 Covid-19 Vaccine against the B.1.1.7 and B.1.351 Variants. 

      Abu-Raddad, Laith J; Chemaitelly, Hiam; Butt, Adeel A ( Massachusetts Medical Society , 2021 , Other)
      The messenger RNA vaccine BNT162b2 (Pfizer–BioNTech) has 95% efficacy against coronavirus disease 2019 (Covid-19). Qatar launched a mass immunization campaign with this vaccine on December 21, 2020. As of March 31, 2021, ...
    • Effectiveness of the neutralizing antibody sotrovimab among high-risk patients with mild-to-moderate SARS-CoV-2 in Qatar 

      Ahmed, Zaqout; Almaslamani, Muna A.; Chemaitelly, Hiam; Hashim, Samar A.; Ittaman, Ajithkumar; ... more authors ( Elsevier , 2022 , Article)
      ObjectivesTo estimate the real-world effectiveness of sotrovimab against severe, critical, or fatal COVID-19 in Qatar at a time in which most SARS-CoV-2 incidences occurred due to the BA.2 Omicron subvariant. MethodsWe ...
    • 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 and Vaccination on Symptomatic Omicron Infections. 

      Altarawneh, Heba N; Chemaitelly, Hiam; Ayoub, Houssein H; Tang, Patrick; Hasan, Mohammad R; ... more authors ( 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 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 ...
    • Epidemiological impact of prioritising SARS-CoV-2 vaccination by antibody status: Mathematical modelling analyses 

      Ayoub, H.H.; Ayoub, Houssein H.; Chemaitelly, Hiam; Makhoul, Monia; Al Kanaani, Zaina; ... more authors ( BMJ Publishing Group , 2021 , Article)
      Background Vaccines against SARS-CoV-2 have been developed, but their availability falls far short of global needs. This study aimed to investigate the impact of prioritising available doses on the basis of recipient ...
    • Immune Imprinting and Protection against Repeat Reinfection with SARS-CoV-2 

      Chemaitelly, Hiam; Ayoub, Houssein H.; Tang, Patrick; Hasan, Mohammad R.; Coyle, Peter; ... more authors ( Massachusetts Medical Society , 2022 , Other)
      More than 2 years into the coronavirus disease 2019 (Covid-19) pandemic, the global population carries heterogeneous immune histories derived from various exposures to infection, viral variants, and vaccination.1 Evidence ...
    • Mathematical modeling of the SARSCoV-2 epidemic in Qatar and its impact on the national response to COVID-19 

      Ayoub, Houssein H.; Chemaitelly, Hiam; Seedat, Shaheen; Makhoul, Monia; Kanaani, Zaina Al; ... more authors ( University of Edinburgh , 2021 , Article)
      Background Mathematical modeling constitutes an important tool for planning robust responses to epidemics. This study was conducted to guide the Qatari national response to the severe acute respiratory syndrome coronavirus ...