Zoonotic Jumps Often Happen Without Special Viral Tweaks
An analysis of outbreaks of influenza A, Ebola, Marburg, mpox, SARS-CoV, and SARS-CoV-2 finds no pre-spillover adaptive mutations; natural selection is normal in animal reservoirs and remains stable before spillover, with most changes occurring after human transmission begins; the study also notes a lab-origin signal for the 1977 H1N1 pandemic, but overall emphasizes reducing exposure and boosting surveillance to prevent future spillovers.
