This cross-sectional study investigates the clinical characteristics and sources of infection of COVID-19 among children and youths in Hong Kong.

Background Pediatric COVID-19 studies exploring the relationships between NPS and saliva viral loads, clinical and immunological profiles are lacking. Methods Demographics, immunological profiles, nasopharyngeal swab (NPS), and saliva samples collected on admission, and hospital length of stay (LOS) were assessed in children below 18 years with COVID-19. Findings 91 patients were included between March and August 20 20. NPS and saliva viral loads were correlated ( r = 0.315, p = 0.01). Symptomatic patients had significantly higher NPS and saliva viral loads than asymptomatic patients. Serial NPS and saliva viral load measurements showed that the log 10 NPS ( r = −0.532, p < 0.001) and saliva ( r = −0.417, p < 0.001) viral loads for all patients were inversely correlated with the days from symptom onset with statistical significance. Patients with cough, sputum, and headache had significantly higher saliva, but not NPS, viral loads. Higher saliva, but not NPS, viral loads were associated with total lymphopenia, CD3 and CD4 lymphopenia (all p < 0.05), and were inversely correlated with total lymphocyte ( r = −0.43), CD3 ( r = −0.55), CD4 ( r = −0.60), CD8 ( r = −0.41), B ( r = −0.482), and NK ( r = −0.416) lymphocyte counts (all p < 0.05). Interpretation Saliva viral loads on admission in children correlated better with clinical and immunological profiles than NPS.

What is already known about this topic? Shrimp allergy is prevalent, but conventional diagnostic methods including skin prick test (SPT) and specific IgE (sIgE) measurements have low specificity. Testing for tropomyosin improves diagnostic accuracy for shrimp allergy in Caucasians, but this has not been replicated among Asians.What does this article add to our knowledge? BAT has superior diagnostic performance for shrimp allergy than SPT and sIgE measurement. Tropomyosin may not be the most appropriate diagnostic marker in the Chinese population. The IgE crosslinkingeinduced luciferase expression (EXiLE) test can be a good alternative to BAT.How does this study impact current management guidelines? A single step of BAT may replace SPT and sIgE in the diagnosis of patients with clinical history suggestive of shrimp allergy. The EXiLE test can be a suitable alternative with respect to cost and sampling constraint.BACKGROUND: The diagnosis of shellfish allergy currently relies on patient history, skin prick test (SPT), and serum specific IgE (sIgE) quantification. These methods lack sufficient diagnostic accuracy, whereas the gold standard of oral food challenges is risky and burdensome. Markers of reactivity and severity of allergic reactions to shellfish will improve clinical care of these patients. OBJECTIVES: This study compared the diagnostic performance of SPT, sIgE, basophil activation test (BAT), and IgE crosslinkingeinduced luciferase expression (EXiLE) test for shrimp allergy. METHODS: Thirty-five subjects with documented history of shrimp allergic reactions were recruited and grouped according to results of double-blind, placebo-controlled food challenge (DBPCFC). In addition to routine diagnostics, BAT (Flow CAST) and EXiLE test with shrimp extract and tropomyosin were performed. RESULTS: Of 35 subjects, 15 were shrimp allergic with pruritus, urticaria, and itchy mouth on DBPCFC, whereas 20 were tolerant to shrimp. Tropomyosin only accounted for 53.3% of sensitization among subjects with challenge-proven shrimp allergy. BAT using shrimp extract as stimulant showed the highest area under curve value (0.88), Youden Index (0.81), likelihood ratio (14.73), odds ratio (104), and variable importance (4.27) when compared with other assays and tropomyosin diagnosis. Results of BAT significantly correlated with those of EXiLE (r [ 0.664, P < .0001). CONCLUSIONS: BAT is a more accurate diagnostic marker for shrimp allergy than SPT and shrimp sIgE, whereas the EXiLE test based on an IgE crosslinking assay is a good alternative to

Background The current diagnostics of fish allergy lack sufficient accuracy such that more reliable tests such as component-resolved diagnosis (CRD) are urgently needed. This study aimed at identifying fish allergens of salmon and grass carp and evaluating the sensitization pattern towards the identified allergens in fish allergic subjects from two distinct populations in Asia. Methods One hundred and three fish allergic subjects were recruited from Hong Kong (67 subjects) and Japan (46 subjects). Western blot and mass spectrometry were used to identify allergens from salmon and grass carp. Fish allergens were purified and tested against 96 sera on ELISA to analyze patients’ sensitization pattern. The protein profiles of salmon meat prepared under different cooking methods until core temperature reached 80°C were evaluated by SDS-PAGE and mass spectrometry. Results Three common allergens between salmon and grass carp, namely enolase, glycerldehyde-3-phosphate dehydrogenase (GAPDH) and parvalbumin, and two salmon-specific allergens collagen and aldolase were identified. Parvalbumin was the major allergen for both fishes showing an overall sensitization rate of 74.7%, followed by collagen (38.9%), aldolase (38.5%) and enolase (17.8%). Japanese subjects showed more diverse allergen sensitization pattern and more frequent IgE-binding to heat-labile salmon allergens. Compared with steaming and boiling, cooking by baking and frying retained more fish proteins inclusive of heat-labile allergens. Conclusions Fish allergic patients from different Asian populations show varying fish allergen sensitization profiles. The relevant extracts and components for diagnosis are population-dependent but parvalbumin and collagen are important biomarkers. Cooking methods modify allergen composition of salmon and appear to influence patients’ allergic manifestations.

The implication of gastrointestinal infection caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its transmission remains to be fully understood. We studied 4 paediatric patients with several weeks of faecal excretion of SARS-CoV-2 RNA who had only mild symptoms. International consensus on isolation practices is urgently needed.