Background: Post-acute sequelae of SARS-CoV-2 infection (PASC) affects patients after recovering from acute coronavirus disease 2019 (COVID-19). This study investigates the impact of SARS-CoV-2 vaccination on PASC symptoms in children in Taiwan during the Omicron pandemic. Methods: We enrolled children under 18 years with PASC symptoms persisting for more than 4 weeks. Data collected included demographics, clinical information, vaccination status, and symptom persistence. We used logistic regression models to compare symptoms in the acute and post-COVID-19 phases and to assess the association between vaccination and these symptoms. Results: Among 500 PASC children, 292 (58.4%) were vaccinated, 282 (52.8%) were male, and the mean (SD) age was 7.6 (4.6) years. Vaccinated individuals exhibited higher odds of experiencing symptoms in the previous acute phase, such as cough (adjusted odds ratio [AOR] = 1.57; 95% confidence interval [CI]: 1.02–2.42), rhinorrhea/nasal congestion (AOR = 1.74; 95% CI: 1.13–2.67), sneezing (AOR = 1.68; 95% CI: 1.02–2.76), sputum production (AOR = 1.91; 95% CI: 1.15–3.19), headache/dizziness (AOR = 1.73; 95% CI: 1.04–2.87), and muscle soreness (AOR = 2.33; 95% CI: 1.13–4.80). In contrast, there were lower odds of experiencing abdominal pain (AOR = 0.49; 95% CI: 0.25–0.94) and diarrhea (AOR = 0.37; 95% CI: 0.17–0.78) in children who had received vaccination during the post-COVID-19 phase. Conclusions: This study revealed clinical features and vaccination effects in PASC children in Taiwan. Vaccination may reduce some gastrointestinal symptoms in the post-COVID-19 phase.

Background: The postacute sequelae of coronavirus disease 2019 (PASC), also known as pediatric long coronavirus disease (COVID), can significantly affect the quality of life (QoL) of affected children. Currently, there are no standardized screening tools to identify high-risk children. The Kinder Lebensqualität fragebogen (KINDL) is a psychometric method for measuring QoL in children.Purpose: This study used the KINDL questionnaire and Children's Somatic Symptom Inventory-24 (CSSI-24) to evaluate symptom burden and establish a screening threshold for pediatric PASC.Methods: We performed a cross-sectional study of children diagnosed with PASC defined as the presence of at least one persistent symptom lasting more than 4 weeks after a confirmed COVID-19 infection. Symptoms were assessed using a structured checklist developed by our team. The correlation between the KINDL and CSSI-24 scores was analyzed, and receiver operating characteristic (ROC) curve analysis was used to determine the optimal KINDL cutoff for identifying high-risk cases. QoL scores were also compared with those of historical cohorts to evaluate the impact of the PASC.Results: We included 84 participants: 46 children (mean age, 8.74±1.77 years; 41.3% girls) and 38 adolescents (mean age, 14.50±1.56 years; 44.7% girls). KINDL and CSSI-24 scores showed a significant negative correlation (r=-0.44, P<0.001), suggesting that increased somatic symptoms were associated with a reduced QoL. The ROC analysis identified a KINDL cutoff score of 74.75 (area under the curve, 0.82) for detecting high-risk children. Compared to historical cohorts, children with PASC had QoL scores comparable to child-reported norms from 2010 but lower than parent-reported norms from the same year.Conclusion: KINDL and CSSI-24 are practical tools for screening for pediatric PASC in outpatient settings. A KINDL cutoff of 74.75 may help clinicians identify children with PASC who require early intervention. Further studies in larger and more diverse populations are required to validate these findings.

Post-acute sequelae of SARS-CoV-2 infection (PASC), also known as long COVID syndrome (LCS), is characterized by persistent symptoms following SARS-CoV-2 infection and poses significant health challenges, particularly impacting pulmonary function in children. This study aims to evaluate the effect of COVID-19 vaccination on pulmonary function in children with PASC using standardized spirometry and impulse oscillometry (IOS). This prospective, observational study was conducted from July to September 2022, at the tertiary medical center of a children's hospital in Taiwan. Pediatric patients aged 6 to 18 years diagnosed with PASC were enrolled. Demographic data, vaccination status, and blood test results were collected. Pulmonary function was assessed using spirometry and IOS, measuring parameters such as respiratory resistance (R5, R20) and reactance (X5). Statistical analyses explored the association between IOS results and clinical symptoms, as well as vaccination status. Among 209 children, 78.7% were vaccinated. IOS detected abnormalities in 74.6%, with 12.0% diagnosed with obstructive lung disease (OLD) and 62.9% with small airway disease (SAD). Fatigue (56.0%) and dyspnea (52.0%) were most common in OLD, while chest pain (45.0%) and cough (41.7%) prevailed in SAD. Vaccinated children showed significantly lower respiratory resistance (R5, R20, p < 0.01) and improved reactance (X5, p < 0.001). Vaccination did not significantly reduce respiratory-related symptoms but it was associated with lower risks of decreased appetite (OR = 0.399) and sleep disturbance (OR = 0.345). COVID-19 vaccination may have a protective effect on pulmonary function in children with PASC, highlighting its mitigation of long-term respiratory complications. Further studies are needed to explore underlying mechanisms.

Background: The clinical features and risk factors of post‑acute sequelae of SARS‑CoV‑2 infection (PASC) in children remain incomplete. This study aims to clarify the manifestations and identify predictors of PASC in pediatric patients previously hospitalized for COVID‑19. Methods: We conducted this retrospective cohort study at the China Medical University Children’s Hospital in Taiwan, including 143 children aged 3-18 hospitalized for the acute COVID-19 during the Omicron pandemic from April 2022 to July 2023. PASC was assessed through phone calls, online survey, and in-person follow-ups. Data encompassing demographics, clinical presentations, laboratory results, and acute-phase treatment were collected and compared between children with and without PASC. Each child was assigned total clinical scores based on the acute-phase symptoms and treatment. We evaluated the association of the total clinical scores with PASC among study children. The receiver operating characteristic (ROC) analysis was used to determine the optimal cutoff for total clinical scores, which best differentiated occurrence of PASC. Results: Among the 143 discharged children, 35.7% (n = 51) developed PASC. Children with PASC tended to be older (mean age: 7.6 vs. 6.3 years, p = 0.05) and greater body weight (29.1 vs. 23.7 kg, p = 0.05). PASC children exhibited higher reverse transcriptase-polymerase chain reaction (RT-PCR) cycle threshold (Ct) values (17.1 vs. 14.2, p = 0.04) during the acute phase than those without PASC. There were no significant disparities in other laboratory results, length of intensive care unit (ICU) stays, bacterial coinfections, oxygen supplementation, and medication usage between two groups. Notably, compared to the control group, the total clinical scores were significantly higher in the PASC group (37.9 vs. 31.5, p = 0.02), with an optimal cutoff value of 37.7 yielding an area under the curve (AUC) of 0.70. Conclusions: This study identified a significant proportion of children developing PASC following hospitalization for acute COVID-19. Older age, greater body weight, and larger RT-PCR Ct values during the acute phase emerged as potential risk factors for developing PASC. Moreover, the clinical scoring system constructed in this study may help to predict the risk of developing PASC after discharge.