There is a lack of evidence of the health impacts due to long COVID among children and young people (CYP). The objective of this study is to determine the main clinical characteristics of long COVID in CYP and to investigate the academic, social, and health status impacts of long COVID in this population. An observational, descriptive, and longitudinal study on CYP who presented COVID-19 symptoms for more than twelve weeks after SARS-CoV-2 infection was performed between December 2020 and May 2021. Fifty CYP were included, with a median age of 14.1 years, 33 (66%) were female, and 17 (34%) had a relative diagnosed with long COVID. Since the initial infection and up to the first visit, CYP had persisting symptoms for a median of 4.1 months, and for 18 (36%) CYP these symptoms persisted for more than 6 months. Fatigue (100%), neurocognitive disorders (74%), muscular weakness (74%), and headache (72%) were the most reported symptoms. A total of 9 (18%) CYP could not attend school, 17 (34%) had a reduced schedule, 33 (66%) showed a decreased school performance, and 68% had stopped extracurricular activities. This preliminary study shows the impact that long COVID has on the health, academic, and social life of CYP.

Background/Objectives: Lack of objective evidence exists regarding changes in physical function and impact on daily functioning in paediatric post-COVID-19 condition (PPCC). This study aimed to assess exercise capacity, fatigue, and peripheral and respiratory muscle strength in PPCC patients compared with healthy controls. Additionally, the impact of PPCC on domains of daily life was evaluated. Methods: A cross-sectional study was performed. Study variables: exercise capacity (6 min walk test, 6MWT), inspiratory muscle strength (maximal inspiratory pressure, PImax), handgrip strength (handheld dynamometer, HHD), quadriceps femoris muscle thickness (QF MT), rectus femoris muscle thickness (RF MT), rectus femoris cross-sectional area (RF CSA), rectus femoris echo-intensity (RF EI), fatigue (Paediatric Functional Assessment of Chronic Illness Therapy-Fatigue, pedsFACIT-F), and physical activity (Assessment of Physical Activity Levels Questionnaire, APALQ). Results: A total of 115 PPCC patients and 227 healthy controls were included. The PPCC group had lower 6MWT (509.00 ± 86.12, p < 0.001), PImax (68.71 ± 26.23, p < 0.001), HHD (82.84 ± 29.09, p < 0.001), APALQ (7.94 ± 3.14, p < 0.001), pedsFACIT-F (24.51 ± 11.01, p < 0.001), QF MT mid-thigh (33.21 ± 7.99, p = 0.011), and higher RF EI (p < 0.001) vs. controls. Only 37.63% of the PPCC group resumed previous sports, 43.48% were unable to attend school full-time and 28.7% could not participate in after-school activities. Conclusions: Paediatric post-COVID-19 condition patients exhibited significant impairments in terms of physical function, with a high impact on daily functioning. This knowledge is necessary to provide targeted therapeutic interventions.

The biological mechanisms underlying long COVID in the pediatric population are poorly understood. Our study aimed to characterize the immune pathophysiology of long COVID in this population. We analyzed major immune cell compartments in PBMCs and the specific SARS-CoV-2 antibody response in 99 patients with long COVID and in 18 patients without long COVID at 3 months after acute infection. Our findings indicate that pediatric long COVID is associated with a dysregulated immune response characterized by altered innate immunity and overactivated T, B, and NK cell responses. Furthermore, young people with long COVID had an impaired humoral response to SARS-CoV-2 marked by a dysregulated B cell compartment and lower levels of anti-RBD IgG and IgA. This correlated with reduced neutralizing capacity against SARS-CoV-2. Random forest analysis identified CCR6 expression on myeloid cells as the most relevant biomarker that distinguishes individuals with long COVID from control individuals with 79% accuracy.

Background/Objectives: Evidence on pulmonary rehabilitation (PR) in paediatric post-COVID-19 condition (PPCC) is scarce. This study aimed to evaluate the association of a PR programme with changes in physical and mental health and quality of life in PPCC over a 12-month follow-up. Methods: A quasi-experimental pre–post single-arm study was conducted, with no control group, in PPCC patients attending an outpatient PR unit. The primary outcome was change in exercise capacity (6 min walk test, 6MWT). Secondary outcomes included inspiratory and peripheral muscle strength, quadriceps muscle morphology by ultrasound, fatigue, physical activity, quality of life, and psychiatric symptoms, assessed using validated paediatric instruments. Results: A total of 115 PPCC patients (mean age 13.3 years; 66.1% female) completed the PR. 6MWD distance increased from 509 ± 87 to 546 ± 86 (+37 m; p < 0.001; D: 0.50). Handgrip strength increased by 2.4 kg, maximal inspiratory pressure increased by 15 cmH₂O, physical activity increased by 2.4 points, fatigue score improved by 9.3 points, and quality of life improved by 11 points (all p < 0.001). Rectus femoris thickness increased by 0.56 mm (p = 0.005), psychiatric symptom scores decreased by 4.5 points (p < 0.001), and rectus femoris echo-intensity decreased (p = 0.003). Conclusions: Multidisciplinary PR appears feasible and potentially effective in improving physical function, psychological well-being, and quality of life in PPCC, supporting the need for evidence-based paediatric rehabilitation.