International Travel

Ra

My little niece will be 7 wks when I return from traveling abroad. I cant find any information on how long to stay away to prevent any illness. Is there any recommendation? I know when we went to visit her in the hospital they asked if anyone had been out of the country in the last 3 weeks. Is that the recomend time to keep away? I will be traveling to Australia but I know there will be people from all over on the plane.