The association of the Epstein Barr Virus (EBV) and multiple sclerosis is one that has evolved over of decades of research. 95% of all humans carry the dormant or "latent" EBV virus. But in people with MS, there is an activation of the virus, which is seen in tissue of autopsied brains.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2118531/
I wrote about this connection exactly 10 years ago. https://ccsviinms.blogspot.com/2012/01/hypoxia-reactivates-latent-ebv-january.html
EBV is in the news a decade later, because researchers at Harvard have a new study published in Science https://www.science.org/doi/10.1126/science.abj8222
Their conjecture is that if people are never infected with EBV, they will never develop MS. Well, that would be wonderful! Incredible. An end to MS. An EBV vaccine will be developed, and it may well help future generations. But what about the people alive today on the planet, the 95% of us who are already infected with EBV?
Back in 2011, researchers at Buffalo Neuroimmaging Analysis Center published a paper in Expert Reviews on how venous stasis (or impeded blood flow out of the brain) might be responsible for a reactivation of EBV. This paper no longer exists online, which is heart-breaking to me. The only place I found links to this hypothesis was in my writing.
But I would like to suggest that this be further explored.