Last year, for the first time ever, the number of people who died from measles globally fell below 100,000. Until widespread vaccination in the 1980s, this virus killed as many as 2.6 million people a year, mainly children.
So, for those of us in global health who have spent decades working to protect children from this terrible disease, today’s announcement marks an important and welcome milestone. But does it now also signal that the end of measles is finally in sight?
The answer to that depends upon not just what happens on the ground in poor countries, where the majority of these deaths occur, but also in the homes and clinics of wealthy nations, across Europe and North America. Because as frontline health workers strive to protect more children in developing countries with vaccines, immunisation coverage in some wealthy countries has been dropping to dangerously low levels. This undermines any progress towards eradication by creating potential havens for the virus and opening up the possibility of developed countries ‘exporting’ the disease to poorer nations.
In 2009, we saw precisely this when the Lancet reported that cases of measles had been exported from Europe to poorer countries in Latin America, a region that had previously eliminated the disease and where higher levels of malnutrition and limited healthcare make the virus far more lethal. This was only made possible because measles is one of the most infectious diseases known to humanity. It is so infectious that it is possible to catch it from someone just by entering the same room, even hours after they have left; measles knows no borders.
And it’s not just poor countries that can be on the receiving end. The UK may have recently celebrated having eliminated measles – which means going three years without a case – but its immunisation coverage remains below the minimum required to provide protection, making it vulnerable to a resurgence. With nearly 10,000 cases and dozens of deaths across Romania, Italy and Germany, if coverage doesn’t start to increase across the country, then it really is just a matter of time before we see measles return to the UK.
To avoid this, vaccination rates need to be above around 95 per cent. This is relatively high compared to other diseases but necessary in order to create herd immunity, where enough of the population is protected to prevent the spread of the virus. The good news is that in the UK 95 per cent of children have indeed received a measles containing vaccine by their fifth birthday. The worrying news is that at age two, just 92 per cent of children are protected, and in the London region less than 90%. Given that the first dose of measles is meant to be given to one-year-olds, the difference suggests that either coverage is beginning to dip or parents may be delaying.
That needs to stop. Because either way, while well-meaning parents may think there is no harm they are effectively creating a window of opportunity for this virus and helping to perpetuate its existence. Globally measles coverage stands at just 85 per cent, which represents progress, but we still have a long way to go to get to 95 per cent in poor countries. Governments like the UK are playing a very active role in helping us get there, by funding routine immunisation programmes across Africa and Asia aimed at boosting protection against measles and other life-threatening diseases.
But if we ever want to eradicate this terrible disease, which has not only killed tens of millions of children in modern times, but also caused blindness or brain damage in countless others, then parents in wealthy countries have to play their part. Because a measles outbreak anywhere is a threat everywhere.