The US just had its first measles death since 2003

This has been a terrible year for measles.

2015 started with one of the worst measles outbreaks in recent history, which originated at Disneyland in California. And on Thursday, the US recorded its first measles death in a dozen years.

According to a news release from the Washington State health department, the (unidentified) woman was probably exposed to the extremely contagious virus while at a medical facility during an outbreak in Clallam County.

Because she was already sick with other health conditions, her immune system was weakened, and she couldn't fight off the disease. She didn't develop the telltale rash — which isn't unusual in patients with already compromised immune systems — but an autopsy later revealed the virus caused the pneumonia that killed her in the spring.

According to the Centers for Disease Control and Prevention, there have been 178 cases of measles in 24 states and the District of Columbia this year. So only six months into 2015, there have already been about as many measles cases as in other recent years with bad outbreaks.

Measles outbreaks, January 1 to June 25, 2015. (CDC)

The spike in 2014 was mostly attributed to the measles virus hitting a group of Amish people in Ohio. That outbreak started when an un-immunized missionary traveled to the Philippines, contracted the disease, and returned only to infect his unvaccinated family and neighbors.

This year, according to the CDC, the majority of people who got the disease were also unvaccinated. These recent, high-profile outbreaks have prompted states to consider vaccine mandates, which force citizens to get shots unless they have a clear medical reason for opting out. This week, California became the third state to impose one on its citizens.

Measles deaths are entirely preventable with vaccines

In the press release, the Washington state health department points out that this measles death was preventable:

This tragic situation illustrates the importance of immunizing as many people as possible to provide a high level of community protection against measles. People with compromised immune systems often cannot be vaccinated against measles. Even when vaccinated, they may not have a good immune response when exposed to disease; they may be especially vulnerable to disease outbreaks.

Measles is prevented through the combination MMR (measles, mumps, and rubella) shot. The CDC recommends that children get two doses, which last for decades. If you're an adult, you should ask your health provider about booster shots.

The vaccine is known to be extremely safe and very effective: It contains a live but weakened version of the virus, which causes your immune system to produce antibodies against measles. Should you be exposed to actual measles, those antibodies will then fire up to protect against the disease.

Again, side effects are rare and mostly very mild. According to the CDC, for example, fevers after the MMR vaccine occur in one out of six people and mild rashes in one in 20. More severe problems are virtually nonexistent: Serious allergic reactions happen in less than one in a million cases. So the benefits of the vaccine — the protection of children and the communities they live in — vastly outweigh the harms.

If too few people get vaccinated, we lose what's known as herd immunity. That's because you need to have a certain level of vaccine coverage in a group in order to stop a disease from spreading. Vaccinated people help prevent diseases from moving through a population and protect those who can't get vaccinated, such as infants or people with medical exemptions.

Most people don't die from measles

In uncomplicated cases, people who get measles start to recover as soon as the rash appears, and they feel back to normal in about two to three weeks.

But up to 40 percent of patients have complications, which usually occur in children under 5, adults over 20, and in anybody else who is undernourished or otherwise immunocompromised.

According to the CDC, the horrible mathematics of measles looks like this: One out of every 20 children with measles will get pneumonia; one in 1,000 will develop encephalitis (swelling of the brain); one or two in 1,000 children will die.

Read more: 9 things everyone should know about measles

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