Joel Pradeepkumar Selvakumar

• Sommen, Silke Lauren; Segtnan, Sunniva; Selvakumar, Joel Pradeepkumar; Havdal, Lise Beier; Stiansen-Sonerud, Tonje & Gjerstad, Johannes [Show all 11 contributors for this article] (2026). Long COVID: Deep single-cell immunophenotyping and machine learning reveal a general signature for fatigue. Journal of Translational Medicine. 24(1). doi: 10.1186/s12967-026-08149-3. Full text in Research Archive
• Øymar, Knut Asbjørn Alexander; Selvakumar, Joel Pradeepkumar; Øymar, Maren Våland; Dalen, Ingvild; Klaseie, Ken Erik & SIVANANTHAM, UJINTHINI [Show all 12 contributors for this article] (2026). High-Flow Nasal Cannula and Continuous Positive Airway Pressure in Infants With Acute Bronchiolitis—Trends of Use in Norway. Acta Paediatrica. ISSN 0803-5253. doi: 10.1111/apa.70643. Full text in Research Archive
• Brodwall, Elias Myrstad; Selvakumar, Joel Pradeepkumar; Havdal, Lise Beier; Sommen, Silke Lauren; Lund-Berven, Lise & Cvejic, Erin [Show all 8 contributors for this article] (2026). Correlates of fatigue in SARS-CoV-2-positive and -negative adolescents and young adults: Repeated cross-sectional analyses from a prospective cohort study. Journal of Psychosomatic Research. ISSN 0022-3999. 209. doi: 10.1016/j.jpsychores.2026.112885. Full text in Research Archive
• Nerli, Tom Farmen; Selvakumar, Joel Pradeepkumar; Heier, Ingar; Johnsen, Tone Langjordet; Wyller, Vegard Bruun Bratholm & Wisløff, Torbjørn (2026). Cost-effectiveness of a brief cognitive-behavioral outpatient rehabilitation program for patients with post-COVID-19 condition within a pragmatic randomized controlled trial. Cost Effectiveness and Resource Allocation. 24. doi: 10.1186/s12962-026-00748-7. Full text in Research Archive
• Raijmakers, Ruud P.H.; Lund-Berven, Lise; Keijmel, Stephan P.; Rodrigo, Chaturaka; Wyller, Vegard Bruun Bratholm & Katz, Ben Z. [Show all 20 contributors for this article] (2025). Immunological associations in post-infective fatigue syndromes including Long COVID—a systematic review and meta-analysis. EBioMedicine. 121. doi: 10.1016/j.ebiom.2025.105970. Full text in Research Archive Show summary

  Background The pathophysiology of post-infective fatigue syndromes (PIFS), including Long COVID, is unknown. This systematic review and meta-analysis aimed to investigate if PIFS is associated with persistent immune activation. Methods PubMed, EMBASE, and Web of Science were searched for terms related to infection, fatigue, persistent symptoms, and immunological markers. Population: adults and adolescents; Exposure: documented acute infection; Comparator: those who developed PIFS vs. recovered controls from the same exposure; and Outcomes: immunological biomarkers. Studies which documented acute infection, applied diagnostic criteria for PIFS, and assayed circulating immunologic markers were eligible. Findings From 14,985 studies screened, 30 articles were included (n = 5102 participants; 833 PIFS/PIFS-like cases, n = 4269 recovered control participants) with many studies excluded by inadequate quality in eligibility criteria. The meta-analysis (11 studies; n = 413 PIFS cases, analysed with random-effects models) showed PIFS cases had increased: white cell counts at 3–6 months (Cohen's d: 0.41, 95% CI 0.09–0.74); and circulating levels of RANTES and TNFα at 6–12 months (Cohen's d: 0.45 [95% CI 0.16–0.73] and 0.30 [95% CI 0.04–0.57], respectively) compared to controls recovered from the same exposure. Interpretation These findings provide cautious support for persistent immune activation in PIFS, but warrant further replication. Future studies should include better documentation of acute infection and PIFS case characterisation. Funding ARL is supported by a National Health and Medical Research Council Practitioner Fellowship (Grant 1041897). CXS is supported by a Cancer Institute New South Wales Early Career Fellowship (2021/ECF1310). BZK is supported by the National Institute of Allergy and Infectious Diseases (AI 105781). RAE is supported by the National Institute for Health and Care.

• Øymar, Maren Våland; Selvakumar, Joel Pradeepkumar; Dalen, Ingvild; Klaseie, Ken Erik; SIVANANTHAM, UJINTHINI & Øvsthus, Kasper Kavli [Show all 12 contributors for this article] (2025). Regional Differences and Time Trends in the Treatment of Infants Hospitalised With Bronchiolitis in Norway. Acta Paediatrica. ISSN 0803-5253. 115(2), p. 378–387. doi: 10.1111/apa.70338. Full text in Research Archive
• Selvakumar, Joel Pradeepkumar; Havdal, Lise Beier; Brodwall, Elias Myrstad; Sommen, Silke Lauren; Lund-Berven, Lise & Stiansen-Sonerud, Tonje [Show all 8 contributors for this article] (2025). Risk factors for fatigue severity in the post-COVID-19 condition: A prospective controlled cohort study of nonhospitalised adolescents and young adults. Brain, Behavior, and Immunity - Health (BBI - Health). 44. doi: 10.1016/j.bbih.2025.100967. Full text in Research Archive Show summary

  Long COVID is a global health concern, leading to persistent symptoms and disability long after the acute SARS-CoV-2 infection in most age groups. The condition can manifest even following mild COVID-19, and in young people, it may have serious adverse consequences for educational attainment and transition to adulthood. Fatigue is the most prevalent symptom, but the underlying mechanisms remain poorly understood. In this prospective study of 404 SARS-CoV-2-positive and 105 SARS-CoV-2 negative, non-hospitalised youth (ages 12–25, female 62%), we investigated which factors in the early convalescent stage (<28 days since test) were associated with the severity of persistent fatigue at 6 months after infection. Participants completed questionnaires regarding clinical symptoms, social factors and psychological traits, and were subject to clinical and functional testing and biomarker analyses. Variables with significant (p < 0.2) associations to the outcome in simple linear regression were chosen for multivariable modelling, together with potential confounders. In the final multivariable model, SARS-CoV-2-positivity was a minor risk factor for fatigue severity at six months. Baseline severity of symptoms was the main risk factor and correlated with psychosocial factors such as loneliness and neuroticism, rather than biomarkers. Our results suggest that factors not related to infection are major risk factors for persistent fatigue in this age group.

• Brodwall, Elias Myrstad; Selvakumar, Joel Pradeepkumar; Havdal, Lise Beier; Sommen, Silke Lauren; Lund-Berven, Lise & Cvejic, Erin [Show all 8 contributors for this article] (2025). Predictors of fatigue progression in long COVID among young people. Brain, Behavior, and Immunity - Health (BBI - Health). 45. doi: 10.1016/j.bbih.2025.100982. Full text in Research Archive Show summary

  Long COVID, or post-COVID-19 condition (PCC), has emerged as a significant health concern, with fatigue being the most prevalent persistent symptom among young people. However, research on predictors of fatigue progression in young populations is limited. This study aimed to investigate factors during acute SARS-CoV-2 infection that could predict fatigue progression between six and 12 months post-infection in a cohort of young people with chronic fatigue following COVID-19. Data from the Long-Term Effects of COVID-19 in Adolescents (LoTECA) project were analyzed. A total of 93 participants (mean age 18.5 years, 84 % female) with chronic fatigue at six months, completed the 12-month follow-up. Multivariate analyses identified non-European ethnicity, higher interferon gamma (IFN-γ) levels, and lower RR-interval (higher resting heart rate) during acute infection as significant predictors of fatigue progression from six to 12 months. These three factors explained 21 % of the variance in the fatigue score, highlighting the importance of ethnicity, immune response, and autonomic function in the trajectory of long COVID fatigue. Early identification and targeted interventions, particularly for ethnic minorities and those with specific immune or autonomic markers during acute infection, may be helpful in reducing long-term fatigue. Further research is needed to explore treatment strategies for affected young populations.

• Havdal, Lise Beier; Selvakumar, Joel Pradeepkumar; Lund-Berven, Lise; Stiansen-Sonerud, Tonje; Zetterberg, Henrik & Blennow, Kaj [Show all 8 contributors for this article] (2024). Neurological involvement among non-hospitalized adolescents and young adults 6 months after acute COVID-19. Frontiers in Neurology. 15. doi: 10.3389/fneur.2024.1345787. Full text in Research Archive Show summary

  Introduction: The post-COVID-19 condition (PCC) is characterized by debilitating persistent symptoms, including symptoms suggesting neurological aberrations such as concentration difficulties, impaired memory, pain, and sleep disturbances. The underlying mechanisms remain elusive. This study aimed to investigate brain injury biomarkers, neurocognitive test performance, and self-reported neurological and neuropsychological symptoms in young people with PCC. Methods: A total of 404 non-hospitalized adolescents and young adults aged 12–25 years who tested positive for SARS-CoV-2, along with 105 matched SARS-CoV-2 negative individuals, were prospectively enrolled and followed-up for 6 months (Clinical Trials ID: NCT04686734). All participants underwent comprehensive assessment encompassing clinical examinations, questionnaires, neurocognitive testing and blood sampling. Serum samples were immunoassayed for the brain injury biomarkers neurofilament light chain (Nfl) and glial fibrillary acidic protein (GFAp). At 6 months, cross-sectional analyses of serum Nfl/GFAp, neurocognitive test results and symptom scores were performed across groups based on adherence to PCC criteria as well as initial SARS-CoV-2 test results. Also, associations between Nfl/GFAp, neurocognitive test results, and symptom scores were explored. Results: A total of 381 SARS-CoV-2 positive and 85 SARS-CoV-2 negative were included in the final analysis at 6 months, of whom 48% and 47%, respectively, adhered to the PCC criteria. Serum levels of Nfl and GFAp were almost equal across groups and did not differ from reference values in healthy populations. Also, neurocognitive test results were not different across groups, whereas symptom scores were significantly higher in patients fulfilling PCC criteria (independent of initial SARS-CoV-2 status). No significant associations between Nfl/GFAp, neurocognitive test results, and symptom scores were found. Conclusion: Normal brain injury biomarkers and neurocognitive performance 6 months after mild COVID-19 implies that the persistent symptoms associated with PCC are not concurrent with ongoing central nervous system damage or permanent disruption of cognitive functions. This finding contradicts the notion of neuroinflammation as a likely explanation for the persistent symptoms.

• Nerli, Tom Farmen; Selvakumar, Joel Pradeepkumar; Cvejic, Erin; Heier, Ingar; Pedersen, Maria & Johnsen, Tone Langjordet [Show all 7 contributors for this article] (2024). Brief Outpatient Rehabilitation Program for Post-COVID-19 Condition: A Randomized Clinical Trial. JAMA Network Open. 7(12), p. 1–16. doi: 10.1001/jamanetworkopen.2024.50744. Full text in Research Archive Show summary

  Importance Post–COVID-19 condition (PCC) is emerging as a common and debilitating condition with few treatment options. Objective To assess the effectiveness of a brief outpatient rehabilitation program based on a cognitive and behavioral approach for patients with PCC. Design, Setting, and Participants Patients with mild to moderate PCC were randomized 1:1 to an established transdiagnostic rehabilitation program or care as usual at a single referral center recruiting from the region of the South-Eastern Norway Regional Health Authority. Participants were followed up after treatment completion and 12 months after enrollment using participant-reported outcome measures. Data were collected from February 22, 2022, until April 15, 2024. Intention-to-treat analysis was performed. Intervention The program consisted of 2 to 8 outpatient encounters with approximately 2 to 6 weeks between each encounter. The intervention was theoretically grounded in the cognitive activation theory of stress, and physicians and physiotherapists were trained in cognitive and behavioral approaches with targeted negative stimuli and response outcome expectancies being particularly important. Main Outcomes and Measures Participant-reported physical function assessed by the Short-Form Health Survey 36 Physical Function Subscale (SF-36-PFS) served as the primary outcome. Secondary outcome measures were the remaining subscales of the SF-36, return to work self-efficacy and symptom scores on fatigue, postexertional malaise, breathlessness, cognitive difficulties, sleep problems, anxiety and depression symptoms, and smell and taste abnormalities. Safety measures included primary health care contacts; hospital admissions; initiation of pharmacologic and/or nonpharmacologic therapy; occurrence of novel disease, illness, or other health problems; worsening of selected key symptoms; working abilities; and thoughts of suicide. Results A total of 473 patients with mild to moderate PCC were assessed for eligibility (n = 364 physician referred; n = 109 self-referred); 314 were included (225 females [72%]; mean [SD] age, 43 [12] years) and 231 completed the primary end point evaluation. The SF-36-PFS scores improved statistically and clinically significantly in the intervention group (score difference between groups, 9.2; 95% CI, 4.3-14.2; P < .001; Cohen d = 0.43; intention-to-treat analysis). The effect was sustained over time. Most secondary and safety measures favored the intervention. Conclusions and Relevance In this randomized clinical trial, a brief outpatient rehabilitation program with a cognitive and behavioral approach in patients with PCC was effective and safe. This trial adds to the evidence supporting such interventions in routine clinical care. Future research should investigate which elements of this approach are the most effective and identify subgroups for which the current treatment is most relevant. Trial Registration ClinicalTrials.gov Identifier: NCT05196451

• Sommen, Silke Lauren; Zhao, Zhi; Segtnan, Sunniva; Stiansen-Sonerud, Tonje; Selvakumar, Joel Pradeepkumar & Havdal, Lise Beier [Show all 9 contributors for this article] (2024). Bulk RNA sequencing for analysis of post COVID-19 condition in adolescents and young adults. Journal of Translational Medicine. 22(1). doi: 10.1186/s12967-024-05117-7. Full text in Research Archive Show summary

  Background Post COVID19 condition (PCC) is a complication of SARSCOV2 infection and can lead to longterm disability. Methods The present study was designed to analyse the gene expression patterns of PCC through bulk RNA sequencing of whole blood and to explore the potential molecular mechanisms of PCC. Whole blood was collected from 80 participants enrolled in a prospective cohort study following SARSCoV2 infected and non-infected individuals for 6 months after recruitment and was used for bulk RNA sequencing. Identification of differentially expressed genes (DEG), pathway enrichment and immune cell deconvolution was performed to explore potential biological pathways involved in PCC. Results We have found 13 differentially expressed genes associated with PCC. Enriched pathways were related to interferon - signalling and antiviral immune processes. Conclusion The PCC transcriptome is characterized by a modest overexpression of interferon-stimulated genes, pointing to a subtle ongoing inflammatory response.

• Olbjørn, Christine; Hagen, Milada; Moen, Aina Elisabeth Fossum; Havdal, Lise Beier; Sommen, Silke Lauren & Lund-Berven, Lise [Show all 10 contributors for this article] (2024). Longitudinal Fecal Microbiota Profiles in A Cohort of Non-Hospitalized Adolescents and Young Adults with COVID-19: Associations with SARS-CoV-2 Status and Long-Term Fatigue. Pathogens. ISSN 2076-0817. 13(11). doi: 10.3390/pathogens13110953. Full text in Research Archive Show summary

  Adolescents most often experience mild acute COVID-19, but may still face fatigue and persistent symptoms such as post-COVID-19 condition (PCC) and post-infective fatigue syndrome (PIFS). We explored the fecal microbiota of SARS-CoV-2 positive and negative non-hospitalized adolescents and young adults (12–25 years of age) in the “Long-Term Effects of COVID-19 in Adolescents” (LoTECA) project, a longitudinal observational cohort study. With a targeted qPCR approach, the quantities of 100 fecal bacterial taxa were measured at baseline (early convalescent stage) in 145 SARS-CoV-2-positive and 32 SARS-CoV-2 negative participants and after six months in 107 of the SARS-CoV-2-positive and 19 of the SARS-CoV-2 negative participants. Results: Faecalibacterium prausnitzii M21.2 and Gemmiger formicilis (both p < 0.001) were enriched in the SARS-CoV-2-positive participants compared to negative controls at baseline. In SARS-CoV-2-positive participants, lower baseline abundance of Faecalibacterium prausnitzii M21/2 (p = 0.013) and higher abundance of Clostridium spiroforme (p = 0.006), Sutterella wadsworthensis (p < 0.001), and Streptococcus thermophilus (p = 0.039) were associated with six-month fatigue. Sutterella wadsworthensis and Streptococcus thermophilus enrichment was additionally associated with PCC in the SARS-CoV-2-positive group (p < 0.001 and 0.042 respectively). Conclusions: Adolescents and young adults with mild acute COVID-19 infection had increased fecal abundance of the beneficial Faecalibacterium prausnitzii M21/2 and Gemmiger formicilis compared to SARS-CoV-2 negative controls in the early convalescent stage. Additionally, the abundance of both known (Faecalibacterium prausnitzii, Streptococcus thermophilus) and new (Clostridium spiroforme, Sutterella wadsworthensis) bacteria were associated with persistent symptoms such as fatigue in the COVID-19 infected group, warranting further exploration of the role of these bacteria in COVID-19 disease and PCC pathophysiology.

• Selvakumar, Joel Pradeepkumar; Havdal, Lise Beier; Drevvatne, Martin Solstrand; Brodwall, Elias Myrstad; Lund-Berven, Lise & Stiansen-Sonerud, Tonje [Show all 19 contributors for this article] (2023). Prevalence and Characteristics Associated With Post-COVID-19 Condition Among Nonhospitalized Adolescents and Young Adults. JAMA Network Open. 6(3). doi: 10.1001/jamanetworkopen.2023.5763. Full text in Research Archive Show summary

  Importance The prevalence and baseline risk factors of post–COVID-19 condition (PCC) remain unresolved among the large number of young people who experienced mild COVID-19. Objectives To determine the point prevalence of PCC 6 months after the acute infection, to determine the risk of development of PCC adjusted for possible confounders, and to explore a broad range of potential risk factors. Design, Setting, and Participants This cohort study included nonhospitalized individuals from 2 counties in Norway between ages 12 and 25 years who underwent reverse transcription–polymerase chain reaction (RT-PCR) testing. At the early convalescent stage and at 6-month follow-up, participants underwent a clinical examination; pulmonary, cardiac, and cognitive functional testing; immunological and organ injury biomarker analyses; and completion of a questionnaire. Participants were classified according to the World Health Organization case definition of PCC at follow-up. Association analyses of 78 potential risk factors were performed. Exposures SARS-CoV-2 infection. Main Outcomes and Measures The point prevalence of PCC 6 months after RT-PCR testing in the SARS-CoV-2–positive and SARS-CoV-2–negative groups, and the risk difference with corresponding 95% CIs. Results A total of 404 individuals testing positive for SARS-CoV-2 and 105 individuals testing negative were enrolled (194 male [38.1%]; 102 non-European [20.0%] ethnicity). A total of 22 of the SARS-CoV-2–positive and 4 of the SARS-CoV-2–negative individuals were lost to follow-up, and 16 SARS-CoV-2–negative individuals were excluded due to SARS-CoV-2 infection in the observational period. Hence, 382 SARS-CoV-2–positive participants (mean [SD] age, 18.0 [3.7] years; 152 male [39.8%]) and 85 SARS-CoV-2–negative participants (mean [SD] age, 17.7 [3.2] years; 31 male [36.5%]) could be evaluated. The point prevalence of PCC at 6 months was 48.5% in the SARS-CoV-2–positive group and 47.1% in the control group (risk difference, 1.5%; 95% CI, −10.2% to 13.1%). SARS-CoV-2 positivity was not associated with the development of PCC (relative risk [RR], 1.06; 95% CI, 0.83 to 1.37; final multivariable model utilizing modified Poisson regression). The main risk factor for PCC was symptom severity at baseline (RR, 1.41; 95% CI, 1.27-1.56). Low physical activity (RR, 0.96; 95% CI, 0.92-1.00) and loneliness (RR, 1.01; 95% CI, 1.00-1.02) were also associated, while biological markers were not. Symptom severity correlated with personality traits. Conclusions and Relevance The persistent symptoms and disability that characterize PCC are associated with factors other than SARS-CoV-2 infection, including psychosocial factors. This finding raises questions about the utility of the World Health Organization case definition and has implications for the planning of health care services as well as for further research on PCC.

• Jankauskaite, Lina; Grechukha, Yevgenii; Kjær, Kristin Avranden; Mamenko, Marina; Nakstad, Britt & Romankevych, Ivanna [Show all 13 contributors for this article] (2022). Overuse of medical care in paediatrics: A survey from five countries in the European Academy of Pediatrics. Frontiers in Pediatrics. 10, p. 1–9. doi: 10.3389/fped.2022.945540. Full text in Research Archive Show summary

  Studies and initiatives such as the “Choosing wisely” (CW) campaign emphasise evidence-based investigations and treatment to avoid overdiagnosis and overtreatment. The perception of the extent of medical overactivity among professionals and drivers behind are not well studied in the paediatric field. Aim We aimed to investigate the physicians‘ opinion and clarify the main drivers regarding medical overactivity in member countries of the European Academy of Paediatrics (EAP). Methods In this study, paediatricians, paediatric residents, primary care paediatricians, and family doctors treating children were surveyed in Norway, Lithuania, Ukraine, Italy, and Switzerland. Over-investigation was defined as “diagnostic work-up or referral that is unlikely to provide information which is relevant for a patient” and overtreatment was defined as “treatment that does not benefit or can harm more than benefit the patient.” The original questionnaire was developed in 2018 by a working group from the Norwegian Paediatric Association. Results Overall, 1,416 medical doctors participated in the survey, ranging from 144 in Lithuania to 337 in Switzerland. 83% stated that they experienced over-investigation/overtreatment, and 81% perceived this as a problem. The majority (83%) perceived expectations from family and patients as the most important driver for overtreatment in their country. Other drivers for overuse were use of national guidelines/recommendations, worry for reactions, and reduction of uncertainty. Conclusion This is the first study investigating knowledge and attitude toward medical overactivity in European countries. Despite different cultural and economic environments, the patterns and drivers of increased investigations and medicalisation are similar.

• Sommen, Silke Lauren; Havdal, Lise Beier; Selvakumar, Joel Pradeepkumar; Einvik, Gunnar; Leegaard, Truls Michael & Lund-Johansen, Fridtjof [Show all 12 contributors for this article] (2022). Inflammatory markers and pulmonary function in adolescents and young adults 6 months after mild COVID-19. Frontiers in Immunology. 13, p. 1–12. doi: 10.3389/fimmu.2022.1081718. Full text in Research Archive Show summary

  Introduction: Both public and scientific attention have shifted from the acute COVID-19 illness to the chronic disability experienced by a proportion of COVID-19 convalescents. Post COVID-19 condition, a term used for long-lasting symptoms after COVID-19, can affect individuals across all disease severity and age groups. Data on post-COVID-19 symptomatology, epidemiology and pathophysiology in adolescents and young adults are scarce. To date, little is known on the immunological and pulmonary trends in these patients after COVID-19. This study investigated immunological markers and pulmonary function in non-hospitalized patients in this group at 6 months after initial mild COVID-19 infection. Methods: Non-hospitalized SARS-CoV-2 positive (n = 405) and SARS-CoV-2 negative (n = 111) adolescents and young adults (aged 12-25 years) were followed prospectively for six months after SARS-CoV-2 PCR testing. At baseline and at six months follow-up, all participants underwent an assessment including clinical examination, questionnaires, spirometry, and blood sampling. Cross-sectional comparisons of blood biomarkers; including white blood cell counts, CRP, GDF-15, a 27-multiplex cytokine assay, complement activation products and SARS-CoV-2 antibodies; and spirometry measures were performed after classification of all participants according to their COVID-19 status and adherence to post-COVID-19 case criteria. Associations between biomarkers and COVID-19 symptoms were explored. Results: No difference in pulmonary function was detected between the groups. COVID-19 convalescents had higher levels of chemokines eotaxin, MCP-1 and IP-10 than non-infected controls. The increase was modest and not associated with long-lasting COVID-19 symptoms. Discussion: Elevated inflammatory mediators were found in adolescents and young adults six months after mild COVID-19, but there was no association with post-COVID-19 condition.

• Havdal, Lise Beier; Berven, Lise; Selvakumar, Joel Pradeepkumar; Stiansen-Sonerud, Tonje; Leegaard, Truls Michael & Tjade, Trygve Olav [Show all 9 contributors for this article] (2022). Neurological Involvement in COVID-19 Among Non-Hospitalized Adolescents and Young Adults. Frontiers in Neurology. 13. doi: 10.3389/fneur.2022.915712. Full text in Research Archive Show summary

  Introduction Coronavirus disease 2019 (COVID-19) is prevalent among young people, and neurological involvement has been reported. We investigated neurological symptoms, cognitive test results, and biomarkers of brain injury, as well as associations between these variables in non-hospitalized adolescents and young adults with COVID-19. Methods This study reports baseline findings from an ongoing observational cohort study of COVID-19 cases and non-COVID controls aged 12–25 years (Clinical Trials ID: NCT04686734). Symptoms were charted using a standardized questionnaire. Cognitive performance was evaluated by applying tests of working memory, verbal learning, delayed recall, and recognition. The brain injury biomarkers, neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAp), were assayed in serum samples using ultrasensitive immunoassays. Results A total of 405 COVID-19 cases and 111 non-COVID cases were prospectively included. Serum Nfl and GFAp concentrations were significantly elevated in COVID-19 cases as compared with non-COVID controls ( p = 0.050 and p = 0.014, respectively). The COVID-19 cases reported more fatigue ( p &amp;lt; 0.001) and post-exertional malaise (PEM) ( p = 0.001) compared to non-COVID-19 controls. Cognitive test performance and clinical neurological examination did not differ across the two groups. Within the COVID-19 group, there were no associations between symptoms, cognitive test results, and NfL or GFAp levels. However, fatigue and PEM were strongly associated with older age and female sex. Conclusions Non-hospitalized adolescents and young adults with COVID-19 reported more fatigue and PEM and had slightly elevated levels of brain injury markers, but showed normal cognitive performance. No associations were found between symptoms, brain injury markers, and cognitive test results, but fatigue and PEM were strongly related to female sex and older age.

• Berven, Lise; Selvakumar, Joel Pradeepkumar; Havdal, Lise Beier; Stiansen-Sonerud, Tonje; Einvik, Gunnar & Leegaard, Truls Michael [Show all 10 contributors for this article] (2022). Inflammatory Markers, Pulmonary Function, and Clinical Symptoms in Acute COVID-19 Among Non-Hospitalized Adolescents and Young Adults. Frontiers in Immunology. 13:837288, p. 1–11. doi: 10.3389/fimmu.2022.837288. Full text in Research Archive Show summary

  Summary: Mild, subacute COVID-19 in young people show inflammatory enhancement, but normal pulmonary function. Inflammatory markers are associated with age and male sex, whereas clinical symptoms are associated with age and female sex, but not with objective disease markers. Background: Coronavirus Disease 2019 (COVID-19) is widespread among adolescents and young adults across the globe. The present study aimed to compare inflammatory markers, pulmonary function and clinical symptoms across non-hospitalized, 12 – 25 years old COVID-19 cases and non-COVID-19 controls, and to investigate associations between inflammatory markers, clinical symptoms, pulmonary function and background variables in the COVID-19 group. Methods: The present paper presents baseline data from an ongoing longitudinal observational cohort study (Long-Term Effects of COVID-19 in Adolescents, LoTECA, ClinicalTrials ID: NCT04686734). A total of 31 plasma cytokines and complement activation products were assayed by multiplex and ELISA methodologies. Pulmonary function and clinical symptoms were investigated by spirometry and questionnaires, respectively. Results: A total of 405 COVID-19 cases and 111 non-COVID-19 controls were included. The COVID-19 group had significantly higher plasma levels of IL-1β, IL-4, IL-7, IL-8, IL-12, TNF, IP-10, eotaxin, GM-CSF, bFGF, complement TCC and C3bc, and significantly lower levels of IL-13 and MIP-1α, as compared to controls. Spirometry did not detect any significant differences across the groups. IL-4, IL-7, TNF and eotaxin were negatively associated with female sex; eotaxin and IL-4 were positively associated with age. Clinical symptoms were positively associated with female sex and age, but not with objective disease markers. Conclusions: Among non-hospitalized adolescents and young adults with COVID-19 there was significant alterations of plasma inflammatory markers in the subacute stage of the infection. Still, pulmonary function was normal. Clinical symptoms were independent of inflammatory and pulmonary function markers, but positively associated with age and female sex.

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• Selvakumar, Joel Pradeepkumar & Wyller, Vegard Bruun Bratholm (2025). ME patient experiences: Sampling bias limits the external validity of findings. Journal of Health Psychology. ISSN 1359-1053. 30(5), p. 1136–1141. doi: https:/journals.sagepub.com/doi/10.1177/13591053241310320. Full text in Research Archive

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