To support the deployment of serology assays for population screening during the COVID-19 pandemic, we compared the performance of three fully automated SARS-CoV-2 IgG assays: Mindray CL-900i® (target: spike [S] and nucleocapsid [N]), BioMérieux VIDAS®3 (target: receptor-binding domain [RBD]) and Diasorin LIAISON®XL (target: S1 and S2 subunits). A total of 111 SARS-CoV-2 RT-PCR- positive samples collected at ≥ 21 days post symptom onset, and 127 pre-pandemic control samples were included. Diagnostic performance was assessed in correlation to RT-PCR and a surrogate virus-neutralizing test (sVNT). Moreover, cross-reactivity with other viral antibodies was investigated. Compared to RT-PCR, LIAISON®XL showed the highest overall specificity (100%), followed by VIDAS®3 (98.4%) and CL-900i® (95.3%). The highest sensitivity was demonstrated by CL-900i® (90.1%), followed by VIDAS®3 (88.3%) and LIAISON®XL (85.6%). The sensitivity of all assays was higher in symptomatic patients (91.1–98.2%) compared to asymptomatic patients (78.4–80.4%). In correlation to sVNT, all assays showed excellent sensitivities (92.2–96.1%). In addition, VIDAS®3 demonstrated the best correlation (r = 0.75) with the sVNT. The present study provides insights on the performance of three fully automated assays, which could help diagnostic laboratories in the choice of a particular assay according to the intended use.

Highlights Performances of five commercial ELISA (EDI, AnshLabs, Dia.Pro, NovaTec, and Lionex) for detecting anti-SARS-CoV-2 IgG was evaluated. Samples used in this study are from diverse national background and the negative group contains samples that are seropositive for all other HCoV. All assays showed low sensitivity during the early stages (≤7 from symptom onset); however, it was greatly improved overtime. Lionex showed the highest specificity (98.6%), followed by EDI and Dia.Pro (97.1%,), NovaTec (85.7%), and AnshLabs (75.7%). Lionex, which measures antibodies to the S1 protein, demonstrated the best performance and doesn’t cross-react with any other HCoV.

schoolchildren in Qatar may be considered as having less overweight and obesity occurrence than most children in the Gulf.

ObjectivesTo investigate the prevalence of vitamin D deficiency among individuals attending primary healthcare facilities in Qatar and to assess the association between vitamin D deficiency and some medical conditions in persons aged 18–65 years old.SettingThe study was undertaken in publicly funded primary healthcare services in the State of Qatar.ParticipantsA total of 102 342 participants aged between 18 and 65 years old with a valid serum vitamin D test result during the year 2017.Outcome measuresSerum level <10 ng/mL (<25 nmol/L) was defined as severe vitamin D deficiency, a serum level of <20 ng/mL (<50 nmol/L) was defined as vitamin D deficiency and a serum level <30 ng/mL (<75 nmol/L) defined as vitamin D insufficiency.ResultsThe prevalence rate of severe vitamin D deficiency was 14.1% among study participants with no history of vitamin D replacement therapy in the previous months. The prevalence rate of vitamin D deficiency was as high as 71.4% and that of vitamin D insufficiency was up to 92.7%. None of the five chronic conditions explored in the study (diabetes, hypertension, asthma, stroke and cardiovascular disease) had an obvious association with severe vitamin D deficiency status in a bivariate analysis. However, multivariate modelling showed that (adjusting for age, gender, body mass index and nationality and each of the included chronic conditions) hypertension, cardiovascular diseases and stroke placed an individual at a higher risk of having an associated severe vitamin D deficiency status.ConclusionAlthough not comprehensive and nationally representative, this study is suggestive of a higher prevalence of vitamin D deficiency among young adults, females, Qatari nationality and those with higher body mass index. Multivariate modelling showed that hypertension, cardiovascular diseases and stroke were associated with a higher risk of severe vitamin D deficiency status.