ITV news report by health correspondent Emily Morgan
The number of measles cases in England is on the rise, almost trebling from 259 cases in England in 2017, to 966 in 2018.
It's a virus that can cause disability and death so what symptoms should you look out for?
Signs and symptoms of measles
Feeling unwell tends to develop around 10 days after being infected. It can feel like a cold or having the flu and you may experience:
Runny or blocked nose
Sore, red eyes
A high temperature (around 40°C)
Small grey/white spots in the mouth
Aches and pains
Loss of appetite
Lack of energy
A few days after initial symptoms, a rash will appear:
red/brown, flat/slightly raised spots that may join together to form larger blotchy patches
usually appears first on the head or neck before spreading
can be itchy
If you have been fully vaccinated with the measles, mumps and rubella (MMR) vaccine or you've had measles before, the rash is unlikely to be caused by the virus.
You should contact a GP as soon as possible if you suspect you or someone you know has measles.
How do you protect children against measles?
The MMR vaccine, which was introduced in 1988, protects against measles, mumps and rubella.
Two doses of the vaccine are required to ensure full protection.
Children are typically given the first injection around their first birthday.
The first MMR jab is sometimes given to younger babies (between 6- to 9-month-old) if they're at high risk of becoming infected in certain circumstances, such as during a measles outbreak.
The second injection is normally given at the age of 3.
If children have not been vaccinated, or only had one of the two doses, they can have a "catch-up" vaccination up to the age of 18.
The World Health Organisation says that 95% of children need to have the vaccine to prevent the disease spreading in the community.
Can adults have the vaccine?
If you've not had the vaccine as a child, you can be given it on the NHS.
People born between 1970 and 1979 may only have been vaccinated against measles. Whilst people born between 1980 and 1990 may not be protected against mumps.
If you are unsure, you can get a vaccine with your GP.
Women planning to get pregnant and who are not already protected are advised to have the jab and should avoid conceiving until a month after the vaccination.
Women who are already pregnant cannot have the jab.
How does the vaccine work?
The MMR vaccine contains weakened versions of live measles, mumps and rubella viruses.
It works by triggering the immune system to produce antibodies against the viruses.
If you come into contact with one of the diseases after the vaccine, your immune system will automatically produce antibodies to fight it.
Are there any side effects to the vaccine?
There can be side effects, but the NHS say the side effects are usually mild.
You could develop a mild form of measles or mumps that last between 1-3 days.
They are not infections.
If you notice a small rash a few weeks after the injection you should see your GP.
How many people are affected by measles?
That was up by 22% from 2017.
Unicef published a list of 10 high-income countries, showing the number of children missing out on their first dose of the vaccine between 2010 and 2017.
The UK was the third most affected country after the US and France.