http://www.aspca.org/pet-care/cat-care/cat-care-herpes.aspx
"Please note, any cat developing an upper respiratory infection should be under veterinary supervision. A brief exam by a veterinarian will help to determine if your cat requires medication, has a fever or is dehydrated. If a cat is just sneezing, but is otherwise acting normally, no treatment will likely be needed. However, if a cat begins to show nasal discharge, loss or appetite or other symptoms, there is evidence of a secondary bacterial infection and cause for starting antibiotics."
I'm of the wait-and-see school, myself. But do know that cats have more likelihood of complication than people.