L-lysine worked for my Epstein-barr virus reactivation after having Covid. I had low grade fever and crushing fatigue for 2 months after recovering from Covid. Every day my temp would be anywhere from 99.0 to 99.8. My normal temp is around 97.5, so it was awful. Vit C helped alot and also NAC, multivitamin, quercitin, CoQ10, B12. But it wasn't until I started taking L-lysine that my low grade fever and fatigue stopped. I'm back to work, have my normal energy, and my temp down to 97s again. I won't start exercising for a while. I want to take it slowly.