New Long COVID-19 Research Identifies Biomarkers, Immune Networks, and Cognitive Therapy

Recent studies have advanced our understanding of Long COVID by identifying blood biomarkers linked to key symptoms, mapping immune networks associated with lung damage, and testing the first empirically supported therapy for cognitive sequelae. Together, these investigations offer a multi‑pronged view of how Long COVID manifests and point to new directions for diagnosis and treatment.

New Biomarker Signature Identified for Long COVID Symptoms
A study in Nature Immunology used ultrasensitive immune and proteomic profiling to compare blood samples from healthy convalescents and individuals with Long COVID. While overall immune cell composition and antiviral T cell responses were similar, healthy convalescents had higher neutralizing antibody levels against SARS-CoV-2. Individuals with Long COVID, especially those with breathlessness, exhibited elevated plasma markers of inflammation and apoptosis, including CCL3, CD40, IL-18, IKBKG and IRAK1, as well as signals of disrupted cell cycle control, lung injury and platelet activation. These findings provide a signature that may underlie specific Long COVID symptoms and lay the groundwork for biomarker-driven diagnostics and targeted therapies.¹

Distinct Immune Pathways Linked to Long COVID Lung Damage
Researchers from UVA Health and collaborators analyzed hundreds of immune features in patients with restrictive lung disease after COVID-19. They identified two phenotypes: one with mild fibrosis and impaired diffusion marked by increased CCR5⁺CD95⁺CD8⁺ T cell activity, and another with severe fibrosis characterized by attenuated T cell responses and elevated CXCL13.² “Our findings reveal crucial differences in the blood that reflect the extent of lung damage,” said Judith A Woodfolk,MD, PhD.³ The team also detected distinct inflammatory mediators and autoantibodies in severe cases, clarifying immunological differences between active lung injury and advanced fibrotic disease. These insights could guide the development of lung-targeted interventions for patients with Long COVID.³

Constraint-Induced Cognitive Therapy Shows Promise for Long COVID Brain Fog
A feasibility trial at the University of Alabama at Birmingham tested Constraint‑Induced Cognitive Therapy (CICT), which pairs behavior‑based coaching with BrainHQ computerized processing exercises, in 16 adults more than three months after COVID‑19. The intervention met all feasibility criteria over 80 percent adherence, high participant satisfaction, and no serious adverse events. It produced large gains in daily living performance (mean improvement 3.7 points on the Canadian Occupational Performance Measure, p < .001, d = 2.6) and reductions in brain fog (mean reduction -4 points on the Mental Clutter Scale, p < .001, d = -2.9). Four of five nonretired participants returned to work after CICT, compared with none in the control group (p = .048).⁴

These results support a larger randomized controlled trial with an active comparison group to confirm CICT’s efficacy and explore its potential as the first empirically supported treatment for Long COVID cognitive sequelae. “This suggests that brain training is a promising approach to helping people with Long COVID,” said Henry Mahncke, PhD, CEO of Posit Science.⁵

References

1. Gao, Y., Cai, C., Adamo, S. et al. Identification of soluble biomarkers that associate with distinct manifestations of long COVID. Nat Immunol 26, 692–705 (2025). https://doi.org/10.1038/s41590-025-02135-5

2. Canderan, G., Muehling, L.M., Kadl, A. et al. Distinct type 1 immune networks underlie the severity of restrictive lung disease after COVID-19. Nat Immunol 26, 595–606 (2025). https://doi.org/10.1038/s41590-025-02110-0

3. University of Virginia Health System. Discovery explains Long COVID breathing problems. Eurekalert. May 5, 2025. Accessed May 5, 2025. https://www.eurekalert.org/news-releases/1082624

4. Long COVID brain fog treatment: An early-phase randomized controlled trial of constraint-induced cognitive therapy signals go. Rehabil Psychol. 2025. doi:10.1037/rep0000626

5. Ericho Communications. Study shows large improvements in Long COVID symptoms and return to work. Eurekalert. May 5, 2025. Accessed May 5, 2025. https://www.eurekalert.org/news-releases/1082652