Read More: Popular Science
Before the measles vaccine existed, 9 out of every 10 kids got the disease before age 15. Two million people died from it every year. It’s easy for most of us to forget that, because we’ve had an effective measles vaccine since 1960. Measles is so infectious that it spreads to 90 percent of those who come in contact with an infected person, though symptoms don’t occur until at least a week later. It starts with the usual: a fever, a cough, a runny nose. A few days later, you develop little white spots inside your mouth. The rash begins soon after. Red dots spread from your hairline all the way down to your feet and your fever spikes, sometimes soaring over 104°F. Most people survive, but if there are complications, death rates can hit up to 30 percent. Pneumonia is the most common fatal side-effect, but patients can also experience swelling of the brain, which can cause permanent deafness or blindness. Prior to the invention of the vaccine, between 15,000 and 60,000 people went blind because of the measles each year. And yet, despite having a cheap way to prevent one of the most infectious diseases in the world, most countries in Europe still haven’t met the target goal for vaccination coverage. That means those countries continue to have deadly outbreaks. That’s why the World Health Organization recently warned that measles is making a comeback in Europe, where most had considered it a thing of the past. Europe reached a record-low number of cases in 2016—just 5,273—but saw a spike up to 21,315 last year.