Many Aucklanders have a lot of questions about the ongoing measles outbreak. The Science Media Centre went to the experts for answers.
From 1 January to 3 September 2019 there have been 975 confirmed cases of measles notified across New Zealand, according to the Ministry of Health. Of these, 812 are in the Auckland region. ESR publicly releases surveillance reports on measles cases every Monday. The Science Media Centre gathered expert comments on the current situation.
Following reports of a measles-infected passenger on a flight from Samoa last week, what is the likelihood the disease will spread to the Pacific?
“Immunisation rates in Samoa have declined significantly since the crisis around the two deaths that occurred. There is a very low level of trust in the health system and in vaccines so addressing the issue there will be a very long hard road. In the meantime, they have many children who will be susceptible to measles. This is deeply concerning, it almost seems inevitable that someone from New Zealand will take the infection into that community. This is like dry tinder waiting for a match. The coverage for the first dose of measles vaccine is about 40%. This has been attributed to the two deaths following an administration error of MMR vaccine.” – Dr Helen Petousis-Harris, University of Auckland
How will we know when NZ loses herd immunity – and what does it mean if that happens?
“Herd immunity, or population protection, occurs when a sufficiently large proportion of a population are immune to prevent the spread of an infectious disease that is passed between people. Because measles is highly infectious the level of immunity to interrupt spread is high, at around 95%. This figure assumes that the immunity is uniformly high, so if there are pockets of lower vaccine coverage (immunity gaps), measles can still spread rapidly in those groups. For a number of reasons, New Zealand has some immunity gaps where measles immunity is significantly lower than 95%, 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.” – Professor Michael Baker, professor of public health, University of Otago, Wellington
“Herd immunity occurs when there are insufficient unvaccinated people in the community for the infectious agent to be able to transmit from one person to another. For something like measles, which is highly infectious, a vaccination rate of 95% is probably needed to protect those such as infants who are vulnerable. The spread of cases suggests we are at the point where herd immunity in some communities has broken down.” – Professor Ross Lawrenson, professor of population health, University of Waikato Medical Research Centre
How long until we lose our measles-free status – and what does it mean if that happens (will that have flow-on effects to things like vaccine funding or Kiwis travelling abroad)?
“Measles elimination is defined as the absence of endemic measles virus transmission in a defined geographical area, such as New Zealand, for 12 months or longer. If a country achieves this interruption of sustained transmission for three years, and can show that it has a well-performing surveillance system, then it is granted elimination status by the regional office of the World Health Organisation (through the Regional Verification Commission for Measles and Rubella Elimination). New Zealand announced this status in October 2017 and has maintained it to the present. The current measles outbreak started in March 2019 so will threaten our elimination status if it continued into early 2020.
“Losing elimination status would have public health and symbolic importance. It would put New Zealand among the group of countries in our region which have poor measles control and are exporters of disease to neighbouring countries, such as Pacific Islands (and apparently to the United States in one recent example). It would also damage our reputation as a relatively good performer in some areas of public health. There would probably be no consequences for New Zealanders travelling overseas unless measles was declared a public health emergency of international concern (which has been proposed by some international commentators).” – Professor Michael Baker
What is the best way to prevent the outbreak in Auckland from spreading further around the country? Do you think we’ll need to say, limit travel to and from Auckland?
“The best way to reduce spread of measles is a systematic and sustained programme of measures to raise immunisation coverage. New Zealand has good infrastructure for delivery of vaccine, including a high level of patient registration with general practices and the National Immunisation Register. These systems can all be used in a concerted way to identify children and young adults who have missed vaccination and get them into their general practices for vaccination. In addition, we need a range of activities to ensure delivery of vaccine to Pacific children and young people who currently have the highest rates of disease.
“Limiting travel to Auckland is not likely to be an effective or practical way of slowing the spread of measles. However, if you are planning on travel to Auckland, or any place in New Zealand or overseas where measles is circulating, you should get vaccinated if you have not had two shots of measles (or MMR) vaccine and you were born after measles vaccination was introduced in 1969. This is an important issue for young children. The first MMR dose is usually given at 15 months of age, but this can be lowered to 12 months or even 6 months if a child is being taken to an area where measles is actively circulating.” – Professor Michael Baker
Are we beyond the stage of tracking the virus?
“We are past the stage of tracking individual chains of measles transmission, but measles is still under close surveillance. It is a notifiable disease and all cases reported by diagnosing doctors and laboratories are recorded on the national notifiable diseases database. This process allows detailed description of the evolving epidemiology of the outbreak. In addition, a sample of viruses are genotyped to add further understanding to the pattern of spread.” – Professor Michael Baker
Professor Michael Baker is a member of the World Health Organisation Regional Verification Commission for Measles and Rubella Elimination.
“In the Auckland region tracing individual cases ceased weeks ago. There is no benefit in tracing cases once you are having as many cases as were are having now. If another case did appear in a new area however, there may well be tracing for that case.” – Dr Nikki Turner, director of the Immunisation Advisory Centre (IMAC) and associate professor in general practice and primary health care, University of Auckland
How can we continue to help people understand the seriousness of the measles situation without creating panic?
“People need to be well informed of the risk, relative to their own personal situation. For those who are vaccinated their actual risk is very low as the vaccine is highly effective with one dose offering 90-95% protection and two doses up to nearly 99% protection. In terms of contact with the virus, for those living outside of the affected regions they need to be reassured that the risk of contracting measles is relatively low. That said, if unimmunised people who are able to be vaccinated understand the seriousness of the disease, we’d expect them to actively seek out the vaccine, regardless of where they are.
“A bit of appropriate panic might not be a bad thing. People also do need to be aware that vaccinating is not only protecting themselves but also stopping the virus spread and therefore protecting others in our community, particularly those who may not be able to have the vaccine such as those who are immune compromised or infants too young to be vaccinated. There is a real community responsibility message here.” – Dr Nikki Turner
“Difficult really. 6% will get pneumonia, some will get inflammation of the brain and one or two in 1000 will die. So far we are lucky to have no deaths. Young babies and the immunocompromised are most at risk.” – Professor Ross Lawrenson
Is there enough vaccine supply? Is there currently any reason people would be being turned away from getting their vaccination?
“We have been informed that currently there are adequate supplies of the vaccine in the country. But 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. 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, who may wish to be extra safe but are presumed to be immune since 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.” – Dr Nikki Turner
“There are currently no issues with MMR vaccine stocks. To support the delivery of childhood vaccinations New Zealand normally uses around 12,000 doses of the MMR vaccine per month. Due to the outbreak New Zealand is now using around 20,000, per month. There are currently over 80,000 doses of the vaccine available in the national vaccine store.” – Lisa Williams, director of operations, Pharmac
Is Pharmac sourcing extra vaccinations from its supplier in anticipation of greater demand?
“Yes, Pharmac is working with the vaccine supplier to obtain additional vaccine stock to meet ongoing increased demand.” – Lisa Williams
Are there any international influences (i.e. outbreaks in the US and UK) that could affect NZ’s supply of the MMR vaccine?
“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.” – Lisa Williams
How will the National Health Coordination Centre help the response?
“The National Health Coordination Centre (NHCC) helps by centralising data across all affected DHBs and developing immunisation responses that are coordinated across geographical DHB boundaries. For example, living in Waikato will of course not keep you safe from the outbreak in Auckland, so being able to coordinate responses across all areas becomes much more effective. It also means that additional resourcing (people and funding) can take the strain off over-worked DHB staff, who can more effectively action plans developed with the NHCC.” – Dr Nikki Turner
Where are the pressure points likely to be for GPs, if the outbreak continues to spread?
“GPs may be asked to provide patients with information about vaccination status. They will also be having pressure to provide additional immunisations for the unvaccinated patients. The most difficult task is diagnosing patients who may have mild symptoms similar to measles.” – Professor Ross Lawrenson
What are some things that the general public can do to make life easier for GPs coping with higher demand for services at the moment?
“Most importantly, don’t walk into your general practice surgery if you suspect your child or you have measles; managing your own self-imposed quarantine if necessary keeps everyone safer. If you’re unsure of your or your family member’s immunisation status, have a good hunt for your Plunket or Well Child book first. If someone has even one documented MMR dose, then they are well sorted in the meantime, the second dose can wait a bit. For general questions about measles, the vaccine and if you need to have a dose – try checking immune.org.nz first and the MoH website. If you can’t find the information you need there, call 0800 IMMUNE to talk to a Healthline nurse.” – Dr Nikki Turner
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