Who is most at risk of measles

It may seem easy to only blame the anti-vaccination movement for the recent rise in measles outbreaks in developed countries. While vaccine resistance may be an important contributor to the problem, it’s important to realise that it’s not just the unvaccinated who pose a risk to public health: many people in Australia may be under-vaccinated without realising it.

Estimates can vary, but for Australian populations, roughly five people out of 100 will not develop full immunity to measles if they’ve only had a single dose of MMR vaccine. However, two doses of the vaccine are effective for more than 99 per cent of the population.

It’s easy to catch up, even if you’re not sure about your vaccination history
The Australian National Immunisation Program recommends that children have a vaccination when they’re 12 months old, and then again at 18 months. Two doses haven’t always been part of the standard vaccination schedule, though, so some people may still not have full protection.

Anyone born after 1966

In Australia, people born before 1966 are generally considered to be immune to measles, as it was highly likely that they had the infection during childhood. After vaccines were introduced and rolled out in the early 1960s, the spread of measles was rapidly reduced.

Two doses, rather than a single shot, were introduced to the National Immunisation Program schedule in the early 1990s. This means there may be people born between 1966 and 1990 without existing immunity from a natural measles infection or due to having missed out on one or two vaccinations.

Thankfully, it’s easy to catch up, even if you’re not sure about your vaccination history. It’s free for anyone born after 1966 to receive a catch-up dose of the measles-containing vaccine (the MMR vaccine) in most Australian states and territories.

Migrants to Australia

If you’ve moved to Australia from another country, you may have missed out on full measles vaccination. Different parts of the world have varying levels of vaccine availability and accessibility. This means that you may not be fully protected against measles infection and should make sure you receive the vaccine here.

Migrants are also more likely to be travelling to visit family and friends overseas. Under-vaccinated travellers are at risk of contracting measles as they pass through crowded environments, such as airports, and visit countries where measles outbreaks are still occurring. This is why making sure your measles vaccinations are up to date, preferably at least two weeks prior to travel, is especially important.

Who should not be vaccinated?

A small proportion of the population cannot safely roll up their sleeves for vaccination against measles. They may have certain medical conditions or be undergoing forms of treatment that damage their immune systems, and as the MMR vaccine contains a live (but weakened) form of the measles virus, it may pose a health risk. If you’re unsure about whether you can safely receive the MMR vaccine, speak with a medical professional.

191003 measles pregnancy risk factors
Women should check their immunisations are up to date before planning a pregnancy. Credit: Walking Photographer / Pexels; CC0

Women who are pregnant should also not receive the vaccine due to possible risks to their unborn baby. It’s important for any women who are trying to fall pregnant to check with their doctor about whether they are already immune to measles. Vaccinations can only be safely given prior to pregnancy.

The protection of these vulnerable people is one of the reasons why it is so important for everyone else to keep their vaccinations up to date to prevent the spread of diseases like measles through the community. Because measles is so contagious, at least 95 per cent of the population need to be vaccinated.

How to check your vaccination history

There are a few different ways you can check whether you’re protected against measles, and your GP can help you do this.

If you grew up in Australia, you might find evidence of immunity in places like a baby health book, which may have been signed or stamped to record childhood vaccinations. Local GPs may also be able to search their own clinic’s records if you’ve had immunisations there in the past. If you’re under 22 years of age, you can also consult the Australian Immunisation Register for records of your vaccinations.

What if you can’t find any evidence of your vaccinations—especially if you came to Australia from another country? Even if you think you have already had two doses of the vaccine, it’s safe to have another dose to be sure that you are fully protected.

The vaccine is also available for free under the National Immunisation Program to refugees and other humanitarian entrants of any age. Check with a medical professional to find out the best way to access the vaccine and make sure you’re protected.

This is part of a series of articles produced by The Australian Academy of Science, funded by the Australian Government.

This article was first published on Australia’s Science Channel, the original news platform of The Royal Institution of Australia.

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