health & science
Measles: What you need to know
How does measles spread?
In the midst of an outbreak, it’s surprising to find out measles has been eliminated in New Zealand. Any outbreak which occurs is caused by somebody infected with measles caught overseas coming into New Zealand.
David Hayman, Massey University Professor of Infectious Disease Ecology, calls measles “one of the most infectious viruses on earth, and possibly the most contagious among people”.
The virus spreads through air and can remain active for a couple of hours outside of the body. Essentially this means you could walk into a room an infected person was in two hours previously and catch the virus. No physical contact with an infected person is necessary.
“Another huge problem, however, is that a large proportion of people become infectious and spread the virus before they develop signs, so they present a risk to others without them or their caregivers knowing it,” said Hayman.
If you’re not fully immunised and come within two metres of an infectious person there’s a 90 percent chance of catching the virus.
Without vaccines or prior exposure to the virus, it’s estimated one person with measles could infect 12 to 18 other people.
What are the symptoms?
Symptoms occur between seven to 18 days after infection. They include a fever, runny nose and cough. Sometimes small white spots will be visible inside the cheeks. A rash will occur between three and seven days of the first symptoms appearing. Normally this starts on the face and travels down the body. People are considered infectious five days before a rash appears until five days after the appearance of the rash.
What should you do if you think you have measles?
If you suspect you’ve got measles call your doctor or call Healthline on 0800 611 116. Do not visit your doctor as you could spread measles to other vulnerable patients. You should stay away from work, school and public places.
How bad is the virus?
Measles can be fatal. One in 10 people who catch measles will need hospital treatment. It can cause permanent hearing loss, brain damage and seizures. Children under five and adults older than 20 are more likely to suffer complications.
A recent study has shown there’s the risk of “immune amnesia” where the immune system is suppressed for several years after being infected with measles.
If you’re pregnant, there’s a risk of miscarriage, premature labour and having a baby with a low birth-weight.
The vaccine cannot be taken during pregnancy.
What's the difference between English measles and German measles?
What was referred to as English measles is now called measles. German measles is a different virus and is referred to as rubella. Rubella is milder but can cause birth defects if caught during pregnancy. The measles mumps rubella (MMR) vaccine protects against both types.
Can you get measles even if you are vaccinated?
There is still a small chance of getting measles after vaccination, but only around 3 percent of people who have had two doses of vaccine will contract it.
Who needs to get vaccinated?
Children should receive two shots of the MMR vaccine. One at 15 months and one at four years. In an outbreak this can be brought forward with the first dose given at 12 months and the second one month after that.
Babies as young as six months can be vaccinated in an outbreak, however, they will still require shots at 15 months and four years.
Do I need a booster?
“Anyone who has only had one measles containing vaccine (MCV) dose needs a booster. Any adult who has had measles itself or had two doses of measles containing vaccine (MCV) is considered immune and does not need to be immunised, except in rare circumstances,” said Hayman.
If you are over 50 you are likely to have been exposed to the virus and don’t require a booster.
The Ministry of Health website says people aged 10 to 29 are most at risk of not being fully vaccinated. As of December 2018, 1.3 million people are in this age bracket.
Those over the age of 29 and under the age of 50 may need a booster shot. Around 1.3 million people are in this age bracket.
If you can’t check your health records through your doctor, or plunket book, the advice is to get vaccinated. There is no harm in getting a booster, even if you are fully immunised.
Hayman explains the need for the booster for older adults:
“Adults who had one vaccine dose are much less at risk than those who have never had any vaccines, but they are more at risk than people that have had two doses. It took some time for health researchers to discover this, so countries like New Zealand that were early to introduce the vaccines are more likely to have cohorts of older people that are not completely protected.”
Immunisation Advisory Centre director Nikki Turner said one of the concerns is, historically, vaccination rates have been low:
“It’s barely more than half of our population. Firstly, we don’t know who has missed out and secondly for people who have had vaccinations, we’re not sure if they have had the correct schedule.”
Over the years, there have been catch-up campaigns, but a national register was only started in 1995.
“If you are in this age range, and you don’t know if you’ve had measles vaccination, the safest option is to get revaccinated,” said Turner.
Do we have enough vaccine for everybody?
Pharmac’s director of operations Lisa Williams said there’s been a higher-than-usual demand for the MMR vaccine in Christchurch.
“National stocks of the MMR vaccine are at normal levels for this time of year and more vaccine (approximately 18,000 doses) is due to arrive in Christchurch by Wednesday this week.”
Pharmac said normally 12,000 doses of the MMR vaccine are used per month. Three months' supply - 36,000 - are held in reserve for outbreaks. Orders to replenish the vaccine arrive monthly.
"Pharmac has processes in place to secure more stock if there is increased demand, and is currently working with suppliers nationally and internationally to get vaccines for everyone who needs them."
Should you rush to the doctor to get your measles vaccination?
For those adults who don't think they've been in contact with someone with the virus and unsure about whether they need to get vaccinated, Turner’s advice is to talk to your doctor.
“You don't have to rush off immediately, but you have to think and get to the doctor within the next few weeks and get your measles status updated.”
For people outside of Christchurch, where the current outbreak is centred, Turner still advises they visit the doctor in the next few months or sooner if planning on travel.
The vaccine is free for those at risk.
What's herd immunity?
When the majority of the population is vaccinated, viruses struggle to spread. For those too young to get vaccinated, or for people whose immune system isn't working well, their only hope is not to catch measles. This means people surrounding them need to get vaccinated. This is referred to as herd immunity.
Health minister David Clark said while New Zealand has high vaccination rates, “we need to do better”. Vaccination rates are in the early 90 percent range but below the target rate.
“There are viruses all around the world and in a global world in which we live, we need to make sure that people are up to date with these schedules.”