Researchers Warn That Immune Changes Linger in Children Long After COVID-19 Recovery
Nikhil Prasad Fact checked by:Thailand Medical News Team Jan 17, 2026 1 hour, 48 minutes ago
Medical News: Brazilian researchers track children’s T-cells for a year
A team of experts from the Universidade de São Paulo Medical School, including the Departamento de Pediatria FMUSP, Hospital das Clínicas HCFMUSP, Instituto da Criança e do Adolescente and the Rheumatology Department at Clinical Hospital, have uncovered important long-term immune changes in children recovering from COVID 19. Their study followed young patients for as long as one year to determine how their T lymphocyte - a core part of the body’s immune defense recovered after infection. This new research brings fresh clarity to how the virus affects children even after the fever and cough are long gone and forms the basis of this
Medical News report.
Researchers find subtle but persistent immune changes in children recovering from COVID 19
Who was studied and why it matters
COVID-19 often hits children more mildly than adults but some fall seriously ill or develop what is known as multisystem inflammatory syndrome in children (MIS-C). The team recruited 50 children and teenagers treated for COVID-19 between 2020 and 2021. Most had underlying conditions including cancer transplants, chronic kidney disease, asthma and autoimmune disorders and almost half were immunosuppressed. A control group of 50 similarly matched children who had never tested positive or shown antibodies was also enrolled. The researchers tracked the study group at two recovery points up to eight months after infection V1 and again at one-year V2 while the controls were assessed once.
T-cells tracked in detail
The scientists used advanced flow cytometry to count different immune cell types including CD3, CD4 and CD8 T cell subsets. They compared how many immune cells were present and which were activated, memory forming or exhausted. They then ran statistical models correcting for age and chronic illnesses to isolate COVID-19 s real impact. In the first visit, MIS-C patients showed strikingly high levels of total white blood cells and lymphocytes. These increases were driven mostly by jumps in several T-cell types. CD3, CD4 and CD8 populations surged along with activated T-cells marked by HLA-DR and antibody supporting follicular helper T-cells all in far higher numbers than in controls.
Memory T cells surged sharply
Children recovering from MIS-C did not show large rises in naïve new immune cells. Instead, they carried swollen ranks of memory T-cells including central memory effector memory and a special type called TemRA that represents T-cells that have fought infection and reshaped themselves for quick future response. These patterns signal a system not just recovering but fully mobilized and still reacting long after symptoms faded.
One year later immune scars remain
By the 12-month visit most inflammation markers faded and many T-cell counts returned near normal. Yet some signals of lingering battle remained. CD8 TemRA cells stayed high and exhausted T-cells increased in bo
th MIS-C and broader COVID-19 groups. Exhausted cells once thought ineffective are now understood as an adaptation to chronic antigen exposure showing the immune system continues recognizing SARS-CoV-2 signals even a year out.
What these findings mean
The researchers conclude that children with mild or moderate COVID-19 generally regain a normal immune balance over time. However, those who experienced MIS- C are left with deeper and longer lasting shifts including elevated T-cell activity and exhaustion markers even 12 months later. These results suggest that severe inflammation in childhood COVID-19 may leave measurable immune footprints long after clinical recovery. The study team stresses that while most young patients heal well, a subgroup especially those with MIS-C or heavy underlying illnesses may benefit from careful long-term follow up to ensure full immune health and to detect rare delayed complications. Their results highlight the importance of immune monitoring in children and demonstrate that pediatric COVID-19 should not be dismissed as uniformly mild because a small fraction can face prolonged biological effects that require attention care and continued research.
The study findings were published in the peer reviewed Journal of Infection.
https://www.sciencedirect.com/science/article/pii/S0163445326000162
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Read Also:
https://www.thailandmedical.news/articles/coronavirus
https://www.thailandmedical.news/articles/long-covid
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