To get full approval they could combine this with animal efficacy studies like they did for the smallpox treatment tecoviromat, since you can’t give smallpox to trial participants either. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6663070/
It turned out to be really useful to have tecoviromat for the recent mpox outbreak
It turned out to be really useful to have tecoviromat for the recent mpox outbreak