A school based measles vaccination programme has started in schools across Teesside, after the number of cases increased again.
There have been 150 confirmed cases of measles in the North East since the recent outbreak.
Almost all the reported cases are on Teesside, with just three in County Durham and none in Newcastle or Gateshead.
The NHS is advising people to contact their GP about vaccinating their children, or to take advantage of the schools programmes.
Parents with children at schools across the Tees Valley are set to receive letters and consent forms over the next few days urging them to take up the offer of the MMR vaccination.
The move follows an outbreak of measles across the North East and is being carried out by the Tees Outbreak Control team.
The team are now introducing a school-based MMR vaccination campaign - to be offered to all children who have yet to be vaccinated against the illness.
The vaccinations will take place across the next few weeks.