Hello. Thank you for your query.
You are absolutely right if the disease you mentioned is contagious like viral infection. A common cold is caused by a bunch of viruses which change their genetic material so frequently. So it has become impossible to discover a vaccine for this. It would be an ideal decision for you to arrange work from home if you suspect that your employees are suffering from any of the contagious diseases and for sure it will prevent others from contracting the disease.
Hope this helps.