Twenty-one children are being kept home from a Melbourne school affected by a measles outbreak until they can prove they are immunised.

More than twenty children have been banned from a Melbourne primary school after two students contracted measles.

Education Minister James Merlino says students and teachers at Princess Hill Primary who can't prove they are fully immunised against the viral infection will have to do their school work from home.

The health department confirmed on Tuesday the two students from Princess Hill Primary School in North Carlton are among five new cases of measles, taking the total affected by an outbreak around the inner-city suburb of Brunswick to 14.

The other 12 cases are adult men and women.

He said 21 students out of 461 at the school will be excluded until March 1.

"Parents must vaccinate their kids," Mr Merlino said.

Health Minister Jill Hennessy says the number of cases is expected to increase.

"Measles is a very dangerous illness, it's highly contagious as well, we know people may not have had symptoms while carrying this illness and that is our great concern," she said.

Ms Hennessy said two people were still in hospital receiving treatment for measles on Tuesday morning.

She urged people to vaccinate their young children and talk with their GPs if they are concerned they may have measles.