Measles in the Pacific via travel from New Zealand

Below are some of the latest numbers around the epidemic of measles in New Zealand, and the outbreaks in Australia which are currently linked to New Zealand via infected travellers. Measles in the pacific is thriving right now.

New Zealand; District Health Boards. Measles is mainly affecting areas around Auckland, North Island.
Source: New Zealand Ministry of Health.

Measles is a vaccine-preventable disease caused by a highly transmissible respiratory virus called measles virus (MeV). When given as two (or three for the very young) doses, the measles vaccine is a highly effective way to prevent disease due to MeV infection.[1]

The measles vaccine is a much safer option to develop immunity than gaining immunity by getting infected by MeV.

Don’t forget measles makes you less immune to other stuff

I recently wrote about a poorly discussed outcome of getting ill with measles; immune amnesia.[2,3]

Not only can a measles infection make you sick, put you in hospital and trigger complications like pneumonia, sepsis and encephalitis, but it can also suppress your immune response to other disease-causing viruses and bacteria.[5] And it can remove the immune defences you had painfully built up from past illnesses.[4] The outcome? You’re left exposed. You may end up getting sick all over again due from infections you were able to fend off – until you got measles. It’s a like a bad morning after but instead of you not knowing what you did last night, it’s your immune response that’s forgotten what it did!

Where are the infections

2019 (red striped bar) is the second-worst year for measles cases in Australia in the past 19 years! Outbreaks have been triggered by contact with a traveller who was infected in a country experiencing their own outbreak. As I write, New Zealand has been a significant source of these travellers. Data source: NNDSS, captured and curated by me.

Cases have been occurring all over Australia this year. The public data in the graphs below – which start from April – highlight a sudden upturn in recent weeks, driven by multiple outbreaks on the eastern (Queensland) and western (Western Australia) coasts of Australia.

Weekly measles infections (also called cases or notifications) in Western Australia and Queensland. Western Australia looks to be controlling their outbreak(s) for now while Queensland’s remains ongoing. Data source: NNDSS, captured and curated by me.

I’ll use a definition of an outbreak as being 1 onward transmission from an infected traveller in a country that has been declared free of endemic MeV transmission (like Australia and New Zealand).

Cumulative confirmed measles notifications have been occurring across most of Australia in 2019, not as ongoing local transmission, but due to importation of virus in infected humans and then some local spread among those who are not suitable immune. Data source: NNDSS, captured and curated by me.

Who is getting infected?

A range of age groups are being infected but the bulk sits among newborns and those who didn’t get both doses of vaccine for reasons that might include…

because they weren’t doing that back in the day
because they didn’t complete the full course in their childhood
because of issues around costs and access to vaccination
because they can’t be vaccinated
because they were too busy to find the time,
because they forgot to get a second dose or can’t remember whether they did or not
because they are hesitant or fearful about this and perhaps other vaccines
because they just don’t care
because they actively avoid all vaccination (in Australia, this is a minority)

Most cases and the highest rates are among males, except in the 10-14-year-olds age group. You can also see that among the older age groups, when measles was rampantly transmitting, cases are few because immunity is high. But as we will learn from the New Zealand data, getting infected at any age is also associated with a decent risk of being admitted to hospital. Vaccination is a much safer way to get that immunity.

The age, sex and rates of notification among Australian measles cases for which this information is available. Data source: NNDSS, captured and curated by me.

What about measles in New Zealand?

New Zealand is experiencing its biggest measle epidemic of the past 11 years-worth of data shown below. Perhaps even longer. We can see this thanks to the public and beautifully prepared weekly reports from the NZ Ministry of Health and the Institute of Environmental Science and Research (ESR) put out.[5,6]

2019 has been a bad year for measles in New Zealand.
Source: New Zealand Ministry of Health.

While it looks like their epidemic has peaked, New Zealand is still seeing over 80 new measles cases a week, so it has a long way to go to quell this infectious wildfire.

Cases are being seen in similar age groups to those seen Australia – kinda everyone (see below).

Most of the activity is in and around Auckland – New Zealand’s largest (but not capital) city in the north of the North Island.

What is really clear among the data is that the majority – 85% of cases for which this information is known – has had no vaccine at all.

Just 4% were partially vaccinated and 11% were fully vaccinated. Cases in these people, sometimes called “breakthrough” cases, do happen. These illnesses could be due to vaccination that didn’t result in immunisation. More likely though they are due to…

prolonged exposure to another infectious person
lots of contact with infectious surfaces
high viral loads

…the kind of interactions you’d find in a family setting.

Measles embers drifting around the Pacific

Buit Australia isn’t the only country seeing cases arrive via travel across its island boundary. Both Tonga [8,9] and Samoa [10,11] have outbreaks linked to the kiwis and Fiji is on alert.[12] I’d strongly suspect that there will also be a fair few cases in Japan – which already outbreaks[13,14] – because of its current Rugby World Cup mass gathering.

Measles has also had a big year in Japan.[14], and that won’t be helped by all the New Zealand visitors there for the Rugby World Cup. There’s also the risk of Japan being a node for dispersal of cases to more countries via newly infected travellers who return home after the Cup.

Vaccination work to prevent disease, save lives and stop the spread. It can also be used with 72 hours after exposure to prevent disease.

Talk to your friends. Stop measles. Keep your immune memories intact.

Get vaccinated.

Virology Down Under

Facts, data, info, expert opinion and a reasonable, occasionally grumpy, voice on viruses: what they are, how they tick and the illnesses they may cause.

Measles in the Pacific via travel from New Zealand

Don’t forget measles makes you less immune to other stuff

Who is getting infected?

What about measles in New Zealand?

Measles embers drifting around the Pacific

Further reading

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Don’t forget measles makes you less immune to other stuff

Who is getting infected?

What about measles in New Zealand?

Measles embers drifting around the Pacific

Further reading

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