Seroprevalence of IgG antibodies against SARS-CoV-2 - a serial prospective cross-sectional nationwide study of residual samples, Belgium, March to October 2020.

BackgroundTo control epidemic waves, it is important to know the susceptibility to SARS-CoV-2 and its evolution over time in relation to the control measures taken.AimTo assess the evolving SARS-CoV-2 seroprevalence and seroincidence related to the first national lockdown in Belgium, we performed a nationwide seroprevalence study, stratified by age, sex and region using 3,000-4,000 residual samples during seven periods between 30 March and 17 October 2020.MethodsWe analysed residual sera from ambulatory patients for IgG antibodies against the SARS-CoV-2 S1 protein with a semiquantitative commercial ELISA. Weighted seroprevalence (overall and by age category and sex) and seroincidence during seven consecutive periods were estimated for the Belgian population while accommodating test-specific sensitivity and specificity.ResultsThe weighted overall seroprevalence initially increased from 1.8% (95% credible interval (CrI): 1.0-2.6) to 5.3% (95% CrI: 4.2-6.4), implying a seroincidence of 3.4% (95% CrI: 2.4-4.6) between the first and second collection period over a period of 3 weeks during lockdown (start lockdown mid-March 2020). Thereafter, seroprevalence stabilised, however, significant decreases were observed when comparing the third with the fifth, sixth and seventh period, resulting in negative seroincidence estimates after lockdown was lifted. We estimated for the last collection period mid-October 2020 a weighted overall seroprevalence of 4.2% (95% CrI: 3.1-5.2).ConclusionDuring lockdown, an initially small but increasing fraction of the Belgian population showed serologically detectable signs of exposure to SARS-CoV-2, which did not further increase when confinement measures eased and full lockdown was lifted.

The 2019 Flemish consensus on screening for overt diabetes in early pregnancy and screening for gestational diabetes mellitus.

Screening for gestational diabetes mellitus (GDM) is important to improve pregnancy outcomes and to prevent type 2 diabetes after pregnancy. The 'International Association of Diabetes and Pregnancy Study Groups' (IADPSG) recommends a universal one-step approach with the 75 g oral glucose tolerance test (OGTT) for screening of GDM. The IADPSG recommendation remains controversial due to the important increase in GDM prevalence and increased workload. After review of the latest evidence and based on data from the 'Belgian Diabetes in Pregnancy' study, members of the Diabetes Liga, the Flemish associations of general physicians (Domus Medica), obstetricians (VVOG), midwives (VVOB), diabetes nurse educators (BVVDV) and clinical chemists (RBSLM) have reached a new consensus on screening for GDM in Flanders. This new consensus recommends universal screening for overt diabetes when planning pregnancy or at the latest at first prenatal contact, preferably by measuring the fasting plasma glucose by using the same diagnostic criteria as in the non-pregnant state. In women with impaired fasting glycaemia, but also in normoglycemic obese women and women with a previous history of GDM, lifestyle counselling is advised with screening for GDM with a 75 g OGTT at 24 weeks. In all other women, we recommend a two-step screening strategy with a 50 g glucose challenge test (GCT) at 24 weeks followed by a 75 g OGTT when the glucose level 1 hour after the GCT ≥130 mg/dl. Diagnosis of GDM is made using the IADPSG criteria for GDM. Postpartum screening for subsequent glucose abnormalities should be advocated and organized for every woman with GDM.