How does a transient viral infection like COVID lead to long lasting neurologic symptoms?

In humans and in animal models, SARS-CoV-2 can damage peripheral sensory nerves in the nose, leaving behind debris that can then trigger inflammation in brain microglia for weeks to months after infection, which can then lead to post-viral neurological symptoms like cognitive dysfunction (brain fog).

The peripheral neuron-to-microglia axis offers a potential explanation for persistent inflammation seen in conditions like Long COVID and ME/CFS.

Researchers used mouse model to study how SARS-CoV-2 infects the brain.

The virus targets neurons but spares blood vessels, triggering neuroinflammation and blood-brain barrier dysfunction.

SARS-CoV-2 quickly invades nerves, reaching the brain before it spreads in blood.

Blocking Neuropilin-1 greatly reduces the virus’s entry into nerve cells.