Debunking measles myths: Is there a vaccine shortage and are you still safe if you were immunised in the 90s?

As the national measles outbreak reaches over 1000 cases, services like Healthline are being bombarded by people concerned for their health and the health of their children.

Here are the answers to three of the most common questions we are hearing when it comes to protection against measles.

ARE WE RUNNING OUT OF VACCINES?

Lisa Williams, director of operations at Pharmac, insists there is plenty of supply.

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"There are currently no issues with MMR vaccine stocks," she said. "There are currently over 80,000 doses of the vaccine available in the national vaccine store."

New Zealand normally uses around 12,000 doses of the MMR vaccine per month for child vaccinations, however due to the outbreak that number is currently around 20,000 per month.

However, having enough is only part of the equation.

"Having enough vaccine on hand is one part of the challenge, getting the vaccine supplies to the right places at the right times, having adequate staff and opportunity to vaccinate are other logistical puzzles to solve," said Nikki Turner, Director of the Immunisation Advisory Centre.

"So while there is currently adequate supplies, to best use the available systems the priority remains to vaccinate those who have no protection.

"Some people may feel they need protection when it is not necessary – those over 50 for example but may wish to be extra safe but are presumed to be immune as they are highly likely to have been exposed to measles when they were young.

"Some parents in areas of low risk may wish to have their 8-month-old vaccinated ahead of the schedule. In both these examples doctors need to balance the concerns of their patients against the likelihood of risk and the resource demands on the system."

Williams said Pharmac was currently working with their international supplier to secure additional vaccines.

"There are measles outbreaks occurring in many countries. But Pharmac is working closely with the supplier to ensure that enough stock is available to continue to meet the increased demand."

ARE WE LOSING HERD IMMUNITY?

Herd immunity is the terms for when such a large percentage of the population are immune to prevent the spread of an infectious disease that it cannot spread widely.

Michael Baker, professor of public health at the University of Otago, said around 95 per cent of the population would need to be immunised against measles in order to establish herd immunity, but parts of New Zealand was currently below that number.

"For a number of reasons, New Zealand has some immunity gaps where measles immunity is significantly lower than 95 per cent, notably in teenagers and younger adults.

"So technically, we have probably never had full herd immunity and the highly infectious measles virus is now finding those immunity gaps," he said.

AM I STILL SAFE IF I WAS IMMUNISED 20+ YEARS AGO?

Anyone un-immunised – babies, older children, teenagers and adults – is at risk of getting sick from measles.

Those who have received the vaccines but have a weak immune system, for reasons such as receiving chemotherapy or radiotherapy for cancer, or taking high-dose steroid medications, may also be at risk.

However, the vast majority of adults are safe. The MMR vaccine (measles, mumps and rubella) is given to children twice, at 15 months and 4 years old. If you were received those vaccines as a child, you are almost certainly safe.

The same applies for anyone who received their first immunisation shots as an adult, which is the case for many people who got vaccinated during the last measles outbreak in the 1990s.

Even receiving one dose of MMR (measles, mumps and rubella) vaccine means you have a 95 per cent chance of being protected.