Flu viruses. Flu viruses capable of being transferred to hands and causing an infection can survive on hard surfaces for 24 hours. Infectious flu viruses can survive on tissues for only 15 minutes. Like cold viruses, infectious flu viruses survive for much shorter periods on the hands. After five minutes the amount of flu virus on hands falls to low levels. Flu viruses can also survive as droplets in the air for several hours; low temperatures increase their survival in the air. Parainfluenza virus, which causes croup in children, can survive for up to 10 hours on hard surfaces and up to four hours on soft surfaces.