AIDS, for instance, also had an extremely high case fatality rate before modern treatment but due to it's slow progression it can spread just fine.
btw, maybe moderna can go after AIDS sometime later? I wonder how mRNA vaccines will work for AIDS patients...
"The development programs announced today are mRNA vaccine candidates against seasonal flu, HIV and the Nipah virus."
(Pedantry: HIV is the virus that causes the disease AIDS. The goal is to prevent AIDS by vaccinating against HIV. It's unlikely that the vaccine would be able to help patients who already have AIDS.)
Props for modesty, I guess, but this is a weird instance to suddenly get coy.
Those two factors mean that it is nearly guaranteed to upset a bunch of religious nutjobs.