Hmm, can you think of a plausible biological mechanism by which a virus could evolve to not cause fever, or to cause fever later than usual? My initial reaction is to be skeptical that fever screening would result in the effects you suggest, mainly because whether or not you get a fever is mostly a function of your innate immune system kicking in and not a function of the virus. Whether or not you get a fever is mostly out of the virus’s control, so to speak. The virus could perhaps evolve methods of evading innate immunity, but other examples I’ve seen of viral adaptation to innate immunity seem like they involve complex mechanisms, which I would guess would not evolve on timescales as short as we’re concerned with here (although here I’d welcome correction from someone with more experience in these matters).
But even if there were potential evolutionary solutions close at hand for a virus to evolve evasion to host innate immune responses, I’m not sure that fever screening would really accelerate the discovery of those solutions, given that the virus is already under such extreme selection pressure to evade host immunity. After all, the virus has to face host immune systems in literally every host, whereas fever screening only applies to a tiny fraction of them.
Hmm, can you think of a plausible biological mechanism by which a virus could evolve to not cause fever, or to cause fever later than usual? My initial reaction is to be skeptical that fever screening would result in the effects you suggest, mainly because whether or not you get a fever is mostly a function of your innate immune system kicking in and not a function of the virus. Whether or not you get a fever is mostly out of the virus’s control, so to speak. The virus could perhaps evolve methods of evading innate immunity, but other examples I’ve seen of viral adaptation to innate immunity seem like they involve complex mechanisms, which I would guess would not evolve on timescales as short as we’re concerned with here (although here I’d welcome correction from someone with more experience in these matters).
But even if there were potential evolutionary solutions close at hand for a virus to evolve evasion to host innate immune responses, I’m not sure that fever screening would really accelerate the discovery of those solutions, given that the virus is already under such extreme selection pressure to evade host immunity. After all, the virus has to face host immune systems in literally every host, whereas fever screening only applies to a tiny fraction of them.