Seventeen people have died from a highly infectious disease in Romania in the last year and a half, in one of the largest outbreaks of this disease last fifty years. 3,446 cases have been reported.

The disease is measles.

It is endemic in Romania, but kept under control through consistent vaccination. Or at least, it was. That vaccination program has faltered in the last few years, and Romanian children are now paying the price.

It gets worse.

According to the European Centre for Disease Prevention and Control, the outbreak is highly likely to be exported to other European countries. And from there, possibly, overseas to the USA and elsewhere.

The outbreak in Romania is a sign of a dangerous trend.

Backsliding on vaccines is a global problem, and one of our greatest global health victories is at risk.

Measles is a virus, and it transmits easily from person to person; it’s one of the most contagious diseases in existence. While measles is often seen as a minor childhood disease, it can be fatal, especially to babies and people facing other health problems. In addition to the risk of death, measles can lead to complications like pneumonia, encephalitis and secondary bacterial infections. It can also cause massive nervous system damage decades after the acute measles infection has resolved.

The vaccine for measles requires two doses. If both doses are given, it is 97% effective against measles. With just one dose, it is 93% effective. This is considered to be a highly effective vaccine.  Vaccination for measles is especially important in Romania, where the virus is endemic – in other words, continuously present in the country. Someone in Romania always has measles, so there is always a risk of being infected.

To prevent endemic measles from turning into an outbreak – or an epidemic – 95% of the population must be fully vaccinated against the virus. From 2005 – 2010, Romania achieved that targeted. Children benefited – the number of measles cases went from 5,647 in 2005 to 352 in 2007 – a massive reduction!

In 2010, however, vaccination coverage numbers began to falter, falling from 95% to 93%. In 2011, Romania reported 4,165 cases of measles. In 2012 Romania reported 6,166 cases of measles and by 2013, vaccination coverage was at 88%. The most recent data we have on measles vaccine coverage is 2015, and it is 86%. It is not a surprise, therefore, that we have a measles outbreak.

What is surprising, perhaps, is the speed with which the outbreak is spreading internationally. Since September 2016, 34 cases of measles with probable links to Romania have been reported in other European countries. Austria, the Czech Republic, France, Germany, Ireland, Italy, Spain and the United Kingdom. Ireland saw an outbreak of 27 cases stemming from the original infection exported from Romania. Belgium faced an outbreak of 75 cases from the first Romanian infection. These numbers are more likely to get worse than better – especially because in Europe, measles is endemic in Belgium, France, Germany, Italy, and Poland as well as Romania.

The measles vaccine is one of the great child survival successes of our time. Measles vaccination became widespread in 1980. Before 1980, measles killed about 2.6 million children every year. In 2015, on the other hand, measles killed 134,200 people. That is a lot of children saved every year as a direct result of the vaccine.

That progress is at risk.

This Romania outbreak might be an anomaly, but it might be something worse. More and more countries, including the US, are seeing their vaccine coverage numbers collapse as parents refuse to vaccinate their children. The European Center for Disease Prevention and Control puts it tactfully, referring to “sub-optimal immunisation coverage in certain population groups due to certain cultural traditions, religious beliefs, fear of adverse effects of the vaccine or lack of confidence in public authorities.” Global health bloggers prefer language along the line of “anti-vaccine nonsense.”

However you describe the phenomenon, in Romania, like the US, people seem to fear vaccines.  Large numbers of parents refuse vaccinations. In Romania, this seems to be due to an unspecified fear of toxins and foreign drug companies. In the US, many parents believe that vaccines cause autism. They do not. (In fact, the most common measles vaccine may actually correlate to a reduced risk of autism.)

Immunization and childhood vaccines have been the core of improving global public health. They’re key to child survival in countries at all income levels. Right now, their power is being eroded by an image problem.  It’s easy to characterize vaccine denialists as a few misguided parents, but their numbers are growing.

Vaccines work when everyone gets them. A few misguided parents making poor choices could lead to the deaths of not just their own children, but many, many more.