I will be honest. This is the study I have been most excited about this week. As someone who spends a probably unhealthy amount of time reading papers, this one genuinely made me stop and reread it twice. It sits at the intersection of everything we have been decoding on this newsletter. Long COVID mechanisms, viral persistence, immune dysregulation. It adds a layer that most people have not considered.
Most adults are carrying multiple dormant viruses right now without knowing it. Epstein-Barr virus, the cause of glandular fever, infects roughly 95% of adults globally and then becomes latent, sitting quietly in B cells indefinitely. Cytomegalovirus infects around 60% of adults in high-income countries and similarly persists lifelong without causing symptoms in immunologically healthy people. Herpesviruses in general follow this pattern: primary infection, then lifelong latency, held in check by a functioning immune system.
What happens to those dormant viruses when the immune system is severely disrupted by a new infection? A study published in Nature in August 2026 by Maguire, Chen, Rouphael and colleagues provides the most comprehensive answer yet, using data from 1,154 people hospitalised with COVID-19 across 20 US hospitals.
