A5059036676- SARS-CoV-2 and COVID-19 Research
- COVID-19 Clinical Research Studies
- Vaccine Coverage and Hesitancy
- SARS-CoV-2 detection and testing
- COVID-19 epidemiological studies
- Respiratory viral infections research
- Viral gastroenteritis research and epidemiology
- Influenza Virus Research Studies
- Bacillus and Francisella bacterial research
- Animal Virus Infections Studies
- vaccines and immunoinformatics approaches
- T-cell and Retrovirus Studies
- Blood groups and transfusion
- Viral Infections and Immunology Research
- COVID-19 and Mental Health
- Zoonotic diseases and public health
- Clostridium difficile and Clostridium perfringens research
- COVID-19 diagnosis using AI
- Animal Disease Management and Epidemiology
- COVID-19 and healthcare impacts
- Advanced Biosensing Techniques and Applications
- Escherichia coli research studies
- Poxvirus research and outbreaks
- Immunodeficiency and Autoimmune Disorders
- Nanowire Synthesis and Applications
Qatar University
2020-2025
Weill Cornell Medical College in Qatar
2022
Ministry of Public Health
2021
Hamad Medical Corporation
2015-2021
Cornell University
2021
Hamad bin Khalifa University
2018-2020
Imperial College London
2015
BackgroundWaning of vaccine protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or disease 2019 (Covid-19) is a concern. The persistence BNT162b2 (Pfizer–BioNTech) effectiveness and in Qatar, where the B.1.351 (or beta) B.1.617.2 delta) variants have dominated incidence polymerase-chain-reaction testing done on mass scale, unclear.MethodsWe used matched test-negative, case–control study design to estimate any SARS-CoV-2 severe, critical, fatal case...
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 omicron (B.1.1.529) variant is unclear.
Waning of vaccine protection against coronavirus disease 2019 (Covid-19) and the emergence omicron (or B.1.1.529) variant severe acute respiratory syndrome 2 (SARS-CoV-2) have led to expedited efforts scale up booster vaccination. Protection conferred by doses BNT162b2 (Pfizer–BioNTech) mRNA-1273 (Moderna) vaccines in Qatar, as compared with two-dose primary series, is unclear.
Abstract 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 the second third/booster doses mRNA COVID-19 vaccines against infections in Qatar. BNT162b2 effectiveness was highest at 46.6% (95% CI: 33.4–57.2%) symptomatic 51.7% 43.2–58.9%) first three months after dose, but declined ~10% or below thereafter. Effectiveness rebounded 59.9% 51.2–67.0%) 43.7% 36.5–50.0%), respectively,...
The effect of prior SARS-CoV-2 infection on vaccine protection remains poorly understood.To assess from breakthrough after mRNA vaccination among persons with vs without infection.Matched-cohort studies in Qatar for the BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) vaccines. A total 1 531 736 individuals vaccinated either between December 21, 2020, September 19, 2021, were followed up beginning 14 days receiving second dose until 2021.Prior COVID-19 vaccination.Incident infection,...
Severe acute respiratory syndrome coronavirus 2 infection from the Omicron variant in children/adolescents is less severe than Delta variant. Those 6 to <18 years also have disease those <6 old. There are limited data assessing 2019 (COVID-19) severity infected with We identified children and adolescents of age (SARS-CoV-2) propensity score-matched controls National COVID-19 Database Qatar. Primary outcome was severity, determined by hospital admission, admission intensive care unit (ICU),...
Abstract Background The future of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic hinges on virus evolution and duration immune protection natural infection against reinfection. We investigated afforded by infection, effect viral evasion reinfection, in Qatar, between 28 February 2020 5 June 2022. Methods Three national, matched, retrospective cohort studies were conducted to compare incidence SARS-CoV-2 disease 2019 (COVID-19) severity among unvaccinated persons...
Key messages and recommendations Thispopulation-based study documentsBNT162b2vaccine protection week-by-week after the first dose. 75% of against infection disease is reached 15-21 daysafter dose. Protection increased most rapidly hospitalization death slowest B.1.351infection.While one dose beyond 21 days could not be assessed, findings support delaying second vaccinedosein situations limited vaccine suppliesand high incidences.
Background: The ongoing pandemic of SARS-COV-2 has already infected more than eight million people worldwide. majority COVID-19 patients either are asymptomatic or have mild symptoms. Yet, about 15% the cases experience severe complications and require intensive care. Factors determining disease severity not yet fully characterized. Aim: Here, we investigated within-host virus diversity in with different clinical manifestations. Methods: We compared genetic 19 27 cases. Viral RNA was...
Abstract The SARS-CoV-2 Delta (B.1.617.2) variant of concern is expanding globally. Here, we assess real-world effectiveness the BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) vaccines against this in population Qatar, using a matched test-negative, case- control study design. any infection, symptomatic or asymptomatic, was 64.2% (95% CI: 38.1-80.1%) ≥14 days after first dose before second dose, but only 53.5% 43.9-61.4%) which large proportion fully vaccinated persons received their...
Abstract SARS-CoV-2 breakthrough infections in vaccinated individuals and those who had a prior infection have been observed globally, but the transmission potential of these is unknown. The RT-qPCR cycle threshold (Ct) value inversely correlated with viral load culturable virus. Here, we investigate differences Ct values across Qatar’s national cohorts primary infections, reinfections, BNT162b2 (Pfizer-BioNTech) mRNA-1273 (Moderna) infections. Our matched-cohort analyses randomly diagnosed...
Abstract 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 the other in Qatar during a large wave, from December 19, 2021 to March 21, 2022. Two national matched, retrospective cohort studies are conducted estimate effectiveness (N = 20,994; BA.1-against-BA.2 study), 110,315; BA.2-against-BA.1 study). Associations estimated using Cox...
Qatar, a country with strong health system and diverse population consisting mainly of expatriate residents, has experienced two large waves COVID-19 outbreak. In this study, we report on 2634 SARS-CoV-2 whole-genome sequences from infected patients in Qatar between March-2020 March-2021, representing 1.5% all positive cases period. Despite the restrictions international travel, viruses sampled populace mirrored nearly entire global population's genomic diversity nine predominant viral...
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 17 but different antigen doses.We assessed the real-world effectiveness infection with severe acute respiratory syndrome 2 (SARS-CoV-2) among Qatar. To compare incidence SARS-CoV-2 national cohort vaccinated participants unvaccinated participants, we conducted three matched, retrospective, target-trial, studies - one assessing data obtained from...
BACKGROUND: Protection offered by five different forms of immunity, combining natural and vaccine was investigated against SARS-CoV-2 Omicron symptomatic BA.1 infection, BA.2 hospitalization death, in Qatar, between December 23, 2021 February 21, 2022. METHODS: Six national, matched, test-negative case-control studies were conducted to estimate effectiveness BNT162b2 (Pfizer-BioNTech) vaccine, mRNA-1273 (Moderna) immunity due prior infection with pre-Omicron variants, hybrid from...
Protection against SARS-CoV-2 symptomatic infection and severe COVID-19 of previous infection, mRNA two-dose vaccination, three-dose hybrid immunity vaccination were investigated in Qatar for the Alpha, Beta, Delta variants.
The COVID-19 pandemic has highlighted the need to use infection testing databases rapidly estimate effectiveness of prior in preventing reinfection ($P{E}_S$) by novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants. Mathematical modeling was used demonstrate a theoretical foundation for applicability test-negative, case-control study design derive $P{E}_S$. Apart from very early phase an epidemic, difference between test-negative $P{E}_S$ and true value minimal became...