Nikhil Prasad Fact checked by:Thailand Medical News Team Jun 04, 2026 1 hour, 34 minutes ago
Medical News: Persistent symptoms in children following COVID-19 infection have puzzled doctors and researchers worldwide. While many young patients recover completely, a subset continues to struggle with fatigue, dizziness, exercise intolerance, cognitive difficulties, headaches, and a range of other symptoms for months after the initial infection. Now, a new study has uncovered biological evidence suggesting that Long COVID in children may be linked to ongoing dysfunction in the body's smallest blood vessels.
New retinal imaging study reveals persistent microvascular abnormalities in children with Long COVID, pointing to
ongoing endothelial dysfunction months after infection
Researchers have found significant abnormalities in the retinal microvasculature—the network of tiny blood vessels located at the back of the eye—in children and adolescents suffering from post-COVID syndrome (PCS), commonly known as Long COVID. The findings provide some of the strongest evidence to date that lingering symptoms in children are associated with measurable physiological changes rather than subjective complaints alone.
The Eye Offers a Window into Blood Vessel Health
The study focused on retinal vessel analysis, a non-invasive technique that allows scientists to examine the body's microcirculation through the blood vessels of the eye. Because retinal vessels closely reflect the condition of blood vessels throughout the body, they can provide important clues about vascular health and endothelial function.
The research was conducted by scientists from the Department of Paediatrics at Jena University Hospital and Friedrich Schiller University Jena, Germany; the University of Applied Sciences Niederrhein, Germany; University Hospital Düsseldorf and Heinrich Heine University Düsseldorf, Germany; the University of Basel, Switzerland; Technische Universität Ilmenau, Germany; Karl Landsteiner University of Health Sciences, Austria; and the AMEOS Hospital Association in Neuburg/Ingolstadt, Germany.
The investigators recruited children and adolescents aged 7 to 17 years who had been diagnosed with post-COVID syndrome and compared them with healthy peers of similar age, sex, and body mass index. The aim was to determine whether Long COVID was associated with persistent changes in microvascular function.
Striking Differences Found in Retinal Blood Vessels
The results revealed a clear and distinct vascular pattern in children with Long COVID.
Compared to healthy controls, affected children had significantly wider retinal arteries and veins. Measurements showed that both the central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) were substantially larger in the Long COVID group. Researchers also found changes in the arteriolar-to-venular ratio, further indicating abnormalities in blood vessel regulation.
Importantly, these differences remained significant even after adjusting for blood pressure and other factors that could influence vessel size. The statistical analysis showed that post-COVID syndrome independently predicted wider retinal
blood vessels, suggesting that the vascular changes were directly associated with the condition itself.
The findings point toward endothelial dysregulation, a condition in which the cells lining blood vessels fail to function normally. The endothelium plays a crucial role in regulating blood flow, inflammation, clotting, and oxygen delivery throughout the body.
Possible Explanation for Long COVID Symptoms
Scientists believe that SARS-CoV-2 can disrupt endothelial function by interacting with ACE2 receptors found on blood vessel walls. This interaction may trigger inflammation, oxidative stress, impaired nitric oxide signaling, and abnormalities in vascular regulation.
Such dysfunction could help explain many symptoms commonly reported in pediatric Long COVID patients. If tiny blood vessels are unable to properly regulate blood flow, tissues and organs may receive less efficient oxygen and nutrient delivery, potentially contributing to fatigue, cognitive difficulties, dizziness, exercise intolerance, and autonomic symptoms.
The study participants were examined nearly a year after their initial COVID-19 infection, with the median interval between infection and the first retinal assessment ranging from approximately 44 to 50 weeks. Despite this long recovery period, the vascular abnormalities remained detectable, highlighting the possibility of persistent microvascular dysfunction long after the virus has cleared.
This
Medical News report notes that the findings support growing evidence from adult Long COVID studies suggesting that endothelial dysfunction may be a central biological feature of post-COVID conditions across different age groups.
Some Children Showed Signs of Improvement
The researchers also conducted follow-up examinations approximately 14 weeks later to determine whether the abnormalities changed over time.
While no major group-wide improvements were observed, the data revealed important individual differences. Children with the most pronounced vessel abnormalities at baseline were often the ones who showed the greatest improvements during follow-up. Those with enlarged retinal veins tended to experience reductions in vessel diameter over time, while children with impaired vascular responsiveness demonstrated signs of recovery in vessel function.
The researchers additionally found that children whose symptoms improved tended to show favorable changes in retinal vascular measurements. Although these findings require further confirmation, they suggest that improvements in symptoms may be accompanied by gradual normalization of microvascular function.
Implications for Future Research and Care
One of the biggest challenges in pediatric Long COVID has been the lack of objective biomarkers that can help physicians understand and monitor the condition. The retinal imaging techniques used in this study may provide a valuable new tool for assessing vascular involvement and tracking recovery.
The findings also strengthen the growing theory that Long COVID is not merely a collection of symptoms but a complex biological condition involving multiple systems, including the vascular system.
Conclusions
This groundbreaking study provides the first direct in-vivo evidence that children and adolescents with Long COVID exhibit persistent abnormalities in retinal microvascular structure that are consistent with endothelial dysfunction. The discovery of enlarged retinal arteries and veins months after infection suggests that subtle vascular disturbances may continue long after the acute illness has resolved. Although some children appeared to experience partial recovery over time, the findings indicate that microvascular regulation remains altered in many affected individuals. These results offer an important biological explanation for persistent symptoms in pediatric Long COVID and may pave the way for new diagnostic approaches, improved monitoring strategies, and future therapies aimed at restoring vascular health in young patients. Larger long-term studies will now be needed to determine how these vascular changes evolve and whether they can predict recovery or disease severity.
The study findings were published in the peer reviewed journal: Scientific Reports.
https://link.springer.com/article/10.1038/s41598-026-54086-y
For the latest on Long COVID, keep on logging to Thailand
Medical News.
Read Also:
https://www.thailandmedical.news/articles/coronavirus
https://www.thailandmedical.news/articles/long-covid
Share
Tweet
Share
