Measles — the canary in the coalmine

One year ago when Japan was officially declared measles-free, the announcement attracted little fanfare. After all, it’s what you might expect of one of the wealthiest nations in the world and the current Group of Seven host. Moreover, with Ebola still fresh in our memories and the continued spread of Zika, measles may seem less of a priority. Far from it, and not just because the disease is one of the most infectious known to humanity, still killing 115,000 people each year. Measles outbreaks are also the closest thing we have to an early warning system against threats to global health security.

Thanks to climate change, mass urbanization, and human and animal migration, changes in the behavior of previously well-understood diseases are now likely, meaning outbreaks could become ever more difficult to anticipate. It will be critically important to have strong defenses in place, which is why we need to pay particular attention to highly infectious diseases such as measles.

Measles is so infectious that it is possible to catch from someone just by entering the same room, even hours after they left. This characteristic makes the disease a good marker to gauge a health system’s readiness to cope with potential global epidemics. The extremely infectious nature of measles means that a much higher level of vaccine coverage is required to achieve “herd immunity” — the point where immunization coverage is high enough within a community to stop the spread of disease. For many common diseases, this threshold is around 80-85 percent; if measles vaccine coverage drops below 90 percent, it is just a matter of time before you will see outbreaks.

This extremely high bar is why some wealthy countries like Japan are only just managing to eliminate measles. It is also why poor countries struggle to do the same. Getting vaccine coverage levels high enough to achieve herd immunity requires several critical elements to be in place. Each can also help prevent the spread of disease that are not vaccine-preventable, but all are extremely challenging for the governments of poor countries to implement.

To some extent this is why, as host of the G-7 summit this year, Japan convened international meetings to discuss universal health coverage last December. Driven by the World Health Organization as well as active supporters like Japan, UHC is ostensibly a push towards ensuring that all countries provide comprehensive health care for all citizens and at an affordable cost.

It is a matter of global equity. However, UHC also has an important role to play in reducing threats to global health security.

By putting the systems in place to ensure populations have access to life-saving health interventions — whether that means treatments for diseases like tuberculosis, diabetes and hypertension, or preventative measures, such as insecticide treated bed nets, nutritional supplements or vaccines — UHC helps to build up resilience to public health threats.

This is partly because having the facilities, personnel and logistics in place improves people’s access to preventive health care, but also because healthier communities are physically less vulnerable to the effects of infectious disease.

This is something Japan knows only too well. When the Ebola epidemic spread across West Africa, Japan’s response was both rapid and generous, putting more than $17 million into the region through my organization, Gavi, the Vaccine Alliance. Since the epidemic ended, Japan has committed a further $18.5 million towards restoring immunizations services in the region. Part of this funding went towards recovery of health systems in the affected countries, while the rest — like much of Japan’s health official development assistance — went towards strengthening health systems across the region.

However, preventing further outbreaks requires more than bricks and mortar. It took more than better hospitals to prevent the further spread of Ebola. Critical elements of defense included robust surveillance to rapidly detect public health risks, personnel trained to recognize and manage potential threats, laboratories capable of identifying diseases quickly and suitable responses plans once the threat was identified.

While some progress has been made towards the universal provision of health care services in poor countries, and to some extent in improving their ability to survey and monitor diseases, many parts of the world are still missing out. Nearly 19 million children globally still do not receive a full course of even the most basic childhood vaccines. And if vaccines are not reaching these children, then it is likely they are also missing out on other vital health care interventions, making them even more vulnerable.

So while countries like Japan have successfully eliminated measles, it’s worth remembering that the Americas achieved the same feat more than a decade ago. Yet year after year, we are still seeing large outbreaks, including a recent death, because of imported cases. Therefore, attention must focus on  where measles outbreaks still occur — not just because of the tens of thousands of lives the disease claims each year, but because these represent the reservoirs of infectious disease for the world.

To do this we need to stop focusing just on catch-up campaigns whenever there is a flare up, and instead concentrate our resources on improving routine immunization to boost population immunity against multiple diseases, and supplement this with campaigns as needed. And in the meantime, whenever and wherever an outbreak occurs we need to treat it as a warning of a potential vulnerability in the preparedness of those countries. In global health security terms, measles is the proverbial canary in the coal mine.

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