More than 400 babies have been infected with the flu in Victoria so far this year and the season's early start has seen huge numbers of children admitted to hospital with the virus.

With the state in the grips of a major flu season that began about three months earlier than usual, Victorian Health Department figures reveal there have been 416 reported cases of influenza in babies under 12 months old, compared to 29 cases at this time last year, an increase of more than 1300 per cent. In 2017, there were 55 cases over the same period.

Data from six major hospitals also shows there have been 338 children admitted for influenza. There had been just 15 at the same time last year.

Associate Professor Margie Danchin, a Royal Children's Hospital paediatrician, says the high number of sick infants highlights how important maternal vaccination is. Credit:Luis Enrique Ascui

Royal Children's Hospital paediatrician and specialist Margie Danchin said the high number of sick infants highlighted the importance of vaccination in young children and expectant mothers.