Nikhil Prasad Fact checked by:Thailand Medical News Team Oct 23, 2025 3 hours, 41 minutes ago
Medical News: A Sudden Rise in Pediatric Stroke Following Chickenpox
A new Danish study has uncovered a surprising and worrying trend: after the COVID-19 pandemic, the number of children in Denmark suffering from strokes linked to chickenpox infections has sharply increased. The study was conducted by researchers from Copenhagen University’s Herlev Hospital, Rigshospitalet, Statens Serum Institut, and Queen Silvia Children’s Hospital at Sahlgrenska University Hospital in Sweden.
Surge in Child Stroke Cases in Denmark Linked to Chickenpox After COVID-19
The researchers examined national health records from 2013 to 2023 to analyze how often children developed a rare type of stroke known as varicella-zoster-virus (VZV) associated arterial ischemic stroke. This
Medical News report found that during the years 2022 and 2023, after pandemic restrictions were lifted, there was a fourfold increase in these stroke cases compared to the pre-pandemic period. The team believes this surge is due to a drop in “herd immunity” after long periods of lockdown and isolation, which reduced children’s natural exposure to common viruses like chickenpox.
What the Study Found
Before the pandemic, Denmark typically recorded fewer than one VZV-related stroke per year among children under 18. However, in just a ten-month period in 2022, doctors identified four cases within a small area north-west of Copenhagen—something the researchers described as “remarkably high.” Nationwide data confirmed this pattern, showing that the overall rate of VZV-associated strokes jumped to about two cases per 100,000 children—four times the pre-pandemic rate.
The children studied were between two and five years old. Most were healthy before their strokes, which developed weeks after having chickenpox. Symptoms included sudden weakness on one side of the body, headaches, dizziness, or brief seizures. Brain scans revealed that the virus caused inflammation in blood vessels, leading to blockages and small areas of brain damage. All the affected children received antiviral and anti-inflammatory treatments and made good recoveries, although two continued to experience fatigue months later.
Possible Causes and Warnings
The scientists say the rise in cases might be linked to what’s known as “immunity debt”—a term describing how reduced exposure to common infections during COVID-19 restrictions led to lower population immunity afterward. When restrictions lifted, more children were infected with chickenpox at an older age, which may have increased their risk of complications.
The study also raises the possibility that COVID-19 itself may have weakened immune defenses, allowing other viruses such as VZV to reactivate. This could explain why similar increases in chickenpox complications have been reported in other European countries like the UK and Poland since 2022.
The Need for Vaccination and Awareness
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Denmark is one of the few Western countries that still does not include the chickenpox vaccine in its national immunization program. The researchers warn that this leaves children vulnerable to both mild and severe VZV complications, including stroke. They suggest that the recent surge in infections and severe cases should prompt renewed discussion about making chickenpox vaccination part of Denmark’s routine child immunizations.
Conclusion
The findings highlight an unexpected health ripple effect from the COVID-19 pandemic—showing how temporary changes in social behavior and immunity can influence other diseases. While the overall number of pediatric strokes remains small, the increase underscores the need for vigilance among doctors and parents. Children showing sudden weakness or unusual neurological symptoms weeks after chickenpox should be examined quickly to rule out stroke. The study also strengthens the argument for preventive vaccination and long-term monitoring of post-pandemic infectious trends.
The study findings were published in the peer reviewed journal: European Journal of Paediatric Neurology.
https://www.sciencedirect.com/science/article/pii/S1090379825001606
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