Several primary school students and a teacher in Tasmania have been hospitalised by a flu outbreak that has affected almost 300 children and staff from the one school.

The Lauderdale Primary School near Hobart is dealing with a suspected Influenza A epidemic with 271 students and 20 staff off sick today - almost half the school's population.

School principal Mike Woods today said several children and one teacher had been treated in hospital for suspected Influenza A.

"Most alarmingly it seems to be affecting young children's breathing and several children have been hospitalised, usually overnight, over the last week, as a precaution," Mr Woods said.

"We did have a staff member admitted to hospital for a couple of nights as well but she's home now.

"Today we have 271 students absent and 20 staff, including 11 classroom teachers."

Mr Woods said symptoms of the virus which started spreading at the school 10 days ago included vomiting, diarrhoea, aches and pains, and headaches.

Health authorities have decided against closing the school unless the situation deteriorates.