If I’m not wrong, fever is a protective mechanism against infections. And the fever is only detrimental if it reaches 40°C and above. Whether symptomless people have a fever or not, I’m not sure as they are probably not tested for fever. But I think symptomless should mean no symptoms, so no fever.

https://medium.com/microbial-instincts/fever-can-hurt-or-help-depending-on-what-started-it-40ac0876105a

I think anything that causes substantial tissue injury will trigger fever. Immune cells and damaged tissues will secrete chemicals that act on the brain’s temperature regulation center to initiate fever.