PECOS Study Details Long-Term Symptom Burden in Pediatric COVID-19 Patients

According to the study authors, a prospective longitudinal analysis of the Pediatric SARS-CoV-2 Outcomes Study (PECOS) has identified 20 symptoms occurring more frequently in children and adolescents with confirmed SARS-CoV-2 infection compared to uninfected controls through 12 months of follow-up, with approximately two-thirds of infected participants reporting at least 1 post-infection symptom at the 12-month visit.¹

The study, published in Pediatric Research, enrolled participants aged 0 to 21 years at Children's National Hospital in Washington, DC, and the National Institute of Allergy and Infectious Diseases at the National Institutes of Health in Bethesda, Maryland.¹ The PECOS longitudinal analysis builds on a previously published cross-sectional baseline report and represents one of the first US prospective studies to follow children systematically with an uninfected comparator cohort through 1 year, using laboratory-confirmed infection status and detailed in-person visits at each time point. Ongoing follow-up through 36 months post-enrollment is in progress.

PECOS (NCT04830852) enrolled participants from July 2021 through June 2023. Children and young adults with laboratory-confirmed SARS-CoV-2 infection were enrolled at least 4 weeks after symptom onset or positive test; uninfected controls had no history of infection and tested negative for both SARS-CoV-2 by RT-PCR and anti-nucleocapsid antibody at enrollment. Of 852 participants completing baseline visits, 705 (83%) were infected, and 147 (17%) were uninfected; 558 infected participants completed the 12-month follow-up visit.

The primary outcome was the presence or absence of each of 50 symptoms drawn from the WHO post-COVID case report form, assessed at baseline, 6 months, and 12 months post-enrollment. Symptom prevalence was compared between cohorts using generalized estimating equations adjusted for age, sex, and pre-existing conditions. A symptom was classified as prevalent in infected participants if it reached statistical significance (P <.05) at either visit, or if it was present in more than 5% of infected participants with an odds ratio of 2.0 or greater at either visit.¹

Clinical findings for symptoms

At baseline, 11 symptoms reached statistical significance in infected compared to uninfected participants, including constitutional symptoms of persistent fatigue (18% vs 5%; OR: 4.60; 95% CI: 2.09–10.13; P <.001), persistent fever (6% vs 1%; OR: 5.06; 95% CI: 1.18–21.72; P = .03), and post-exertional malaise (11% vs 4%; OR: 2.52; 95% CI: 1.06–6.0; P = .04).¹

Gastrointestinal symptoms, including constipation, diarrhea, loss of appetite, and nausea/vomiting; neurologic symptoms of forgetfulness and persistent headache; and respiratory symptoms of persistent dry cough and shortness of breath were also statistically elevated in the infected cohort at baseline. Symptom cluster analysis showed infected participants reported significantly more constitutional, gastrointestinal, HEENT, neurologic, and respiratory symptoms at baseline compared to uninfected controls, with constitutional symptoms remaining statistically elevated at 12 months (30% vs 13%; OR: 2.32; 95% CI: 1.05–5.12; P = .04).¹

Age-stratified symptom patterns and behavioral health findings in PECOS

Age played a critical role in the type, frequency, and trajectory of post-COVID symptoms. Younger children aged 5 years and under were more likely to report persistent fever and dry cough at multiple time points, both of which resolved by month 12. Children aged 6 and older showed a broader and more persistent symptom profile spanning multiple organ systems, including chest pain, dizziness, persistent fatigue, post-exertional malaise, forgetfulness, joint pain, persistent muscle pain, numbness, persistent headache, and shortness of breath. Symptoms with increasing frequency over the 12-month follow-up period included dysmenorrhea (OR: 1.32; 95% CI: 1.04–1.69; P = .02), joint pain (OR: 1.20; 95% CI: 1.03–1.4; P = .02), and persistent headache (OR: 1.20; 95% CI: 1.042–1.373; P = .01), whereas persistent fever and weight loss decreased in frequency over time.¹

A finding with particular clinical significance for ID practitioners and pediatric clinicians involves behavioral health outcomes. Anxiety, depression, and difficulty concentrating were prevalent in both the infected and uninfected cohorts, with no statistically significant difference between groups at either time point.

The study authors interpreted this finding as evidence that these symptoms reflect the broad psychological impact of the pandemic and associated social isolation rather than direct sequelae of SARS-CoV-2 infection. No significant association was identified between symptom presence at 12 months and the predominant viral variant circulating at the time of initial infection, with Omicron and pre-Omicron periods showing comparable symptom profiles.¹

"This study helps us understand how post-COVID symptoms in children evolve over time, and importantly, across different age groups," said Alexandra B. Yonts, MD, of the Division of Pediatric Infectious Diseases at Children's National Hospital and co-lead author, in a statement.² "Since childhood is such a dynamic period of growth and development, tracking these symptoms at multiple time points and in children of many different ages is critical to know what the true long-term impacts of SARS-CoV-2 infection look like in the pediatric population."

Continued PECOS follow-up through 36 months post-enrollment, alongside concurrent cardiac, pulmonary, psychological, developmental, and laboratory assessments, is expected to clarify longer-term outcomes and may yield biospecimens to investigate underlying mechanisms of post-COVID disease in children.¹

REFERENCES

1. Montealegre Sanchez GA, Yonts AB, Mateja A, et al. Pediatric SARS-CoV-2 outcomes study (PECOS): 12-month longitudinal analysis of post-COVID symptoms in infected versus uninfected participants. Pediatr Res. Published May 2, 2026. doi:10.1038/s41390-026-05002-7
2. Children's National Hospital. New research reveals COVID-19's long-term impact on kids. GlobeNewswire. Published May 28, 2026. Accessed May 29, 2026. https://www.globenewswire.com/news-release/2026/05/28/3303108/0/en/new-research-reveals-covid-19-s-long-term-impact-on-kids.html