A new strain of the virus that causes gastro has been identified in Victoria, and the researchers behind the discovery warn it could soon become an epidemic, or even a pandemic.

This strain of norovirus - the most common cause of gastroenteritis - was first detected at a very low frequency in Victoria in August last year but reappeared slightly altered in June. Experts fear this slight change means it could skip around herd immunity.

It is believed to have been responsible for most gastro outbreaks in the state since, sparking a health department warning earlier this month.

Using 14 years of surveillance data from Victoria, the scientists who made the discovery say this strain has the potential to become a pandemic in two to seven months.