I have acquired a head cold this week. Not Covid, just the typical sore throat, followed by sinus and chest congestion. Yay. Oh, how I missed the common cold. It has been too long absent from my life.
The thing about working from home is it made no significant impact on my work schedule. I took a couple of hours to rest one day, then mostly made up the time working longer afterwards. In fact, I worked longer and got more done because I was too miserable (and considerate) to go to the gym. Sitting and writing code was relaxing and productive.
Every tech worker and manager I have known for the last twenty years has done the same thing. Work from home while sick is not a bit deal. Obviously, the kind of illness is a factor. There are days I have simply been sick of work and take a day off. If your employer is debating whether to continue a remote work policy, ask if they themselves would like to work from home if they had a cold or mild illness.
Naturally, I support virtual work and see the benefits. While there are jobs with obvious exceptions to telecommuting, if the job can be dome remotely, what arguments are there against allowing it? Now, solve for the use case.