Most children have a mild course of acute COVID-19. Only few mainly non-controlled studies with small sample size have evaluated long-term recovery from SARS-CoV-2 infection in children. The aim of this study was to evaluate symptoms and duration of ‘long COVID’ in children. A nationwide cohort study of 37,522 children aged 0–17 years with RT-PCR verified SARS-CoV-2 infection (response rate 44.9%) and a control group of 78,037 children (response rate 21.3%). An electronic questionnaire was sent to all children from March 24th until May 9th, 2021. Symptoms lasting > 4 weeks were common among both SARS-CoV-2 children and controls. However, SARS-CoV-2 children aged 6–17 years reported symptoms more frequently than the control group (percent difference 0.8%). The most reported symptoms among pre-school children were fatigue Risk Difference (RD) 0.05 (CI 0.04–0.06), loss of smell RD 0.01 (CI 0.01–0.01), loss of taste RD 0.01 (CI 0.01–0.02) and muscle weakness RD 0.01 (CI 0.00–0.01). Among school children the most significant symptoms were loss of smell RD 0.12 (CI 0.12–0.13), loss of taste RD 0.10 (CI 0.09–0.10), fatigue RD 0.05 (CI 0.05–0.06), respiratory problems RD 0.03 (CI 0.03–0.04), dizziness RD 0.02 (CI 0.02–0.03), muscle weakness RD 0.02 (CI 0.01–0.02) and chest pain RD 0.01 (CI 0.01–0.01). Children in the control group experienced significantly more concentration difficulties, headache, muscle and joint pain, cough, nausea, diarrhea and fever than SARS-CoV-2 infected. In most children ‘long COVID’ symptoms resolved within 1–5 months.Conclusions: Long COVID in children is rare and mainly of short duration. What is Known:• There are increasing reports on ‘long COVID’ in adults.• Only few studies have evaluated the long-term recovery from COVID-19 in children, and common for all studies is a small sample size (median number of children included 330), and most lack a control group. What is New:• 0.8% of SARS-CoV-2 positive children reported symptoms lasting >4 weeks (‘long COVID’), when compared to a control group.• The most common ‘long COVID’ symptoms were fatigue, loss of smell and loss of taste, dizziness, muscle weakness, chest pain and respiratory problems.• These ‘long COVID’ symptoms cannot be assigned to psychological sequelae of social restrictions.• Symptoms such as concentration difficulties, headache, muscle- and joint pain as well as nausea are not ‘long COVID’ symptoms.• In most cases ‘long COVID’ symptoms resolve within 1-5 months.

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Multisystem inflammatory syndrome in children (MIS-C) is a severe disease that emerged during the COVID-19 pandemic. Although recognized as an immune-mediated condition, the pathogenesis remains unresolved. Furthermore, the absence of a diagnostic test can lead to delayed immunotherapy. Using state-of-the-art mass-spectrometry proteomics, assisted by artificial intelligence (AI), we aimed to identify a diagnostic signature for MIS-C and to gain insights into disease mechanisms. We identified a highly specific 4-protein diagnostic signature in children with MIS-C. Furthermore, we identified seven clusters that differed between MIS-C and controls, indicating an interplay between apolipoproteins, immune response proteins, coagulation factors, platelet function, and the complement cascade. These intricate protein patterns indicated MIS-C as an immunometabolic condition with global hypercoagulability. Our findings emphasize the potential of AI-assisted proteomics as a powerful and unbiased tool for assessing disease pathogenesis and suggesting avenues for future interventions and impact on pediatric disease trajectories through early diagnosis.

Disease progression, loss to follow-up, and mortality of HIV-2 compared with HIV-1 in children is not well understood. This is the first nationwide study reporting outcomes in children with the two HIV types in Guinea-Bissau. Nationwide retrospective follow-up study. This is a retrospective follow-up study among HIV-infected children <15 years at nine ART centers from 2006 to 2021. Baseline parameters and disease outcomes for children with HIV-2 and HIV-1 were compared. The annual number of children diagnosed with HIV peaked in 2017. HIV-2 (n = 64) and HIV-1 (n = 1945) infected children were different concerning baseline median age (6.5 vs 3.1 years, P < 0.01), but had similar levels of severe immunodeficiency (P = 0.58) and severe anemia (P = 0.26). Within the first year of follow-up, 36.3% were lost, 5.9% died, 2.7% had transferred clinic, and 55.2% remained for follow-up. Mortality (HR = 1.05 95% CI: 0.53-2.08 for HIV-2) and attrition (HR = 0.86 95% CI: 0.62-1.19 for HIV-2) rates were similar for HIV types. The decline in children diagnosed per year since 2017 is possibly due to lower HIV prevalence, lack of HIV tests, and the SARS-CoV-2 epidemic. Children with HIV-2 were twice as old as HIV-1 infected when diagnosed, which suggests a slower disease progression. However, once they develop immunosuppression mortality is similar.

(1) Background: Post-arrival screening for infectious diseases is routinely offered to newly arrived refugees in Denmark, including tests for hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), and syphilis. This study aimed to examine the cascade of care following positive screening results in a local cohort of refugees in Denmark, with a focus on subsequent clinical management, follow-up, and outcomes. (2) Methods: This retrospective cohort study included 1506 newly arrived refugees of all ages and countries of origin. All were offered a post-arrival infectious disease screening in Denmark. Clinical records were reviewed to assess progression through the cascade of care, including referral, evaluation, follow-up, and clinical outcomes among individuals with positive screening results. (3) Results: Of the 1506 screened refugees, 33 (2.2%) had at least one positive screening result. Among the 15 individuals with detectable hepatitis B surface antigen, six (43%) attended regular follow-up, while eight (57%) were lost during the cascade of care. Two participants screened positive for HCV antibodies; both underwent initial clinical evaluation, but their subsequent care trajectories differed due to repeated non-attendance or undocumented reasons. Only one participant with non-specific syphilis antibodies completed follow-up in accordance with national guidelines. One participant was diagnosed with HIV and successfully linked to care. (4) Conclusions: The prevalence of screened infectious diseases in this local Danish refugee cohort was low and consistent with findings from comparable settings. Although post-arrival screening facilitates the identification of infectious diseases, substantial loss to follow-up occurred after initial diagnosis, limiting the effectiveness of follow-up and treatment. These findings highlight the need for targeted, interdisciplinary strategies addressing organisational, social, and individual barriers to improve continuity of care following screening.

Aim: To describe age‐specific clinical features and identify predictors of length of hospital stay in children and adolescents with primary Epstein–Barr virus (EBV) infectious mononucleosis (IM). Methods: This multicentre retrospective cohort study included all children and adolescents aged 0–17 years with a verified primary EBV infection in the Central Denmark Region between March 2020 and March 2025. Results: Among 1657 serologically verified primary EBV infections, 307 patients (18.5%) required EBV‐related hospitalisation. Hospitalisation incidence increased with age. Although adolescents accounted for most EBV‐related admissions (77.5%), EBV‐infected children below 7 years were hospitalised more often (one in four) than children aged 7 years or older (one in seven). The most common presenting symptoms were tonsillitis (77%), fever (75%) and lymphadenopathy (64%). Hepatic dysfunction was frequent, particularly among adolescents, whereas anaemia and hyperbilirubinemia occurred more often in younger children. Prolonged length‐of‐stay was independently associated with hyperbilirubinemia, elevated C‐reactive protein, organomegaly and secondary bacterial infection. Conclusion: Disease severity in paediatric EBV infection was associated with inflammatory and hepatic complications rather than age. Early identification of these features may support risk stratification and optimise inpatient care.