United Airlines policy on Travellers with Chicken Pox?

Hi, My son has chicken pox and we're due to fly to America on Tuesday. We're scheduled to visit our GP on Monday to confim whether he's out of the contagious stage and fit to fly (If he is we'll get a dr's note as confirmation and take it with us). Does anyone know what United Airline's policy is on this type of thing? Are we OK to fly as soon as no longer contagious? Any info would be much appreciated. Thanks.