Measles vaccination

Measles is caused by the measles virus, which occurs in humans everywhere in the world, except where almost 100% of the population has been vaccinated.

Measles is a virus that only causes infection in humans, but it has relatives that infect animals, notably the virus that causes the disease distemper in dogs and the virus causing rinderpest in cattle.

Measles virus is spread in droplets from the nose and throat of people with measles. Another person in the vicinity breathes in these droplets and the virus infects the surface cells of that person’s upper airways.

The spreading of the disease from person to person is assisted by the fact that a runny nose with sneezing, as in the beginnings of a cold, and coughing occur in the early stages of the illness. A person is infectious from about three days before the rash appears and for up to five days after its appearance.

Measles is highly contagious and almost everyone coming into contact with an infectious person will contract the disease, unless they have had measles before or have been vaccinated.

The earliest symptoms of measles are:

• High fever, rising over 3 days to 39 to 40.5 degrees Celsius
• Runny nose
• A harsh, dry cough
• Red, inflamed eyes (conjunctivitis) and aversion to bright light

After these symptoms begin, small white spots (sand-grain size) on a red base can be seen upon careful examination of the inside of the mouth, usually opposite the molar teeth on the inside of the cheeks. These are known as Koplik’s spots.

They are unique to measles and can therefore confirm the diagnosis of measles if an experienced health care professional identifies them. However, they appear and disappear in the space of less than a day and can easily be missed.

The symptoms above become increasingly severe and are at their worst when the rash appears. The rash of measles starts along the hairline of the neck and from behind the ears, and then spreads rapidly, within 24 hours, over the entire face, upper arms and chest. Over the next 24 hours it spreads over the back, stomach and thighs, eventually reaching the feet on the third day.

The rash starts as faint spots, which then become reddish and is raised. As the rash progresses the individual spots characteristically tend to merge into one another and in severe cases the whole face may be swollen and disfigured. Once the rash reaches the feet, there is usually a sudden improvement, including a drop in temperature. (If the temperature does not drop at this point, a complication should be suspected.) The rash will start to fade and turn brownish, and some peeling occurs.

It's useful to remember that although the process isn't visible, the rash is occurring internally as well, throughout the respiratory tract and the gut. This explains the cough and diarrhoea that may also occur.

How the measles vaccine works
The measles vaccine is a live measles virus that has been severely "handicapped" or attenuated by culturing techniques in the laboratory. After inoculation, the measles vaccine virus will infect a person and cause the proper, protective immune response to measles without causing measles.

However, up to 20% of people contract a mild fever and rash, usually six to eight days after vaccination. Unfortunately, about one per million people who have the vaccine get an "allergic" type of encephalitis (compared to the 1/1 000 risk after natural measles infection) and there is also a one per million risk of SSPE.

Measles vaccine is recommended for children with HIV infection because they are at risk for severe measles and they tolerate the vaccine well.

Measles vaccination in Australia
Measles is a vaccine-preventable disease and measles vaccination is recommended as part of routine childhood immunisation. It's listed on the National Immunisation Program Schedule and funded for children under the Immunise Australia Program.

To receive measles immunisation, visit your local doctor or immunisation provider.

Immunisation against measles is achieved using the MMR and MMRV combination vaccines. The first dose is given at 12 months of age as the MMR vaccine and the second dose is given at 18 months of age as the MMRV vaccine.

If your child is aged over 18 months at 1 July 2013, they will receive the second dose at four years of age as the MMR vaccine, as per the previous NIP schedule. This schedule point will remain until 31 December 2015.