This appears to relate to a residential situation. Is there a lease, tenancy, rental, homeowners or condo agreement? That would be the first place to look. If such an agreement exists and there is a clause requiring residents to report contracting contagious viruses then there should be no reason it’s not enforceable. If it’s been agreed to I can see no reason why enforcing the clause would be illegal. Absent such a clause I don’t see any basis for the request and in that case it could probably be ignored.