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Background: Rapid antigen testing (RAT) is one of the most powerful tools for SARS-CoV-2 detection. The OnSite COVID-19 Ag Rapid Test is an antigen-based, point-of-care test approved by the WHO for Emergency Use Listing. The Nucleocapsid ( N ) gene mutations found in the emerging Omicron sublineages lead to the question of RAT performance., Objective: To ensure the diagnostic performance of the study RAT during rapidly mutated Omicron variants., Results: We independently evaluated the performance of this assay in 1098 archived samples collected in Thailand during October 2022-February 2023, which were 798 and 300 COVID-19 real-time RT-PCR positive and negative, respectively. The assay performed with 100% sensitivity and 100% specificity using a cycle threshold (Ct) of <20 for the RT-PCR. The sensitivity decreased to 88% when using Ct <30. Most of the SARS-CoV-2 found were Omicron BA.2 (99%), harboring six known N mutations (P13L, E31del, S33del, R203K, G204R and S413R). Eight samples containing hybrid variants (XBB.1*, XBB.2 and XBJ) were detected by the study RAT. This RAT detects all Omicron sublineages known to be circulating in Thailand., Conclusions: These results confirmed the good performance of the study RAT for detecting Omicron variants and its appropriateness for individual diagnosis and for genomic surveillance.

The prevalence of anemia is high in the population of Myanmar and hypochromic microcytic anemia (HMA) is predominant. The objective of our study was to determine the prevalence of anemia and causes of HMA among school children. A cross-sectional study was conducted on 239 children from Thanlyin and Insein Townships, Yangon Region, Myanmar. Complete blood count (CBC) and blood film morphology was examined on venous blood samples. Hypochromic microcytic anemia cases were subsequently analyzed for serum ferritin and cellulose acetate hemoglobin (Hb) electrophoresis. The prevalence of anemia was 46.4%; 27.6% had mild, while 18.8% had moderate anemia, and no case of severe anemia was detected. The mean Hb concentration was 11.7 ± 0.9 g/dL. The younger age group (8-11 years) had a significantly higher prevalence of anemia than the older age group (12-15 years) (p = 0.029). Blood film morphology revealed a 50.6% red blood cell (RBC) disorder; HMA was the most common type (70.2%). Out of 85 children with HMA, three children (3.5%) had iron deficiency and all had comorbidity with Hb AE (β A /β E ) (Hb E trait). Hemoglobin electrophoresis illustrated that Hb AA (β A /β A ) (31, 36.5%) and Hb AE (β A /β E ) trait (31, 36.5%) were the most common types followed by β-thalassemia (β-thal) trait (19, 22.3%) and Hb EE (β E /β E ) (homozygous Hb E; HBB: c.79G>A) (three, 3.5%). Hematocrit [or packed cell volume (PCV)], mean corpuscular volume (MCV), mean corpuscular Hb (MCH) and mean corpuscular Hb concentration (MCHC), showed a significant difference between Hb AE, Hb EE and β-thal trait (p = 0.029, 0.023, 0.015 and 0.01, respectively). Our findings will provide valuable information for the management of anemia in the Myanmar school-age population.