More than 41,000 people in Europe were infected with measles during the first half of 2018, according to the WHO, smashing 12-month totals for any year since 2010.

Expand chart Data: World Health Organization; Chart: Chris Canipe/Axios

Why it matters: Measles is a preventable disease with a highly effective vaccine, but medically unfounded skepticism about the vaccine's link to autism have reduced vaccination rates below the effective threshold to protect many communities.

By the numbers: The measles outbreak so far this year is staggering.

Previously, the highest number of cases in a year was 23,927, recorded last year.

According to the WHO, 34 fatalities have occurred from the ongoing outbreak.

Seven European countries have had more than 1,000 cases reported so far this year, including: France, Georgia, Greece, Italy, Russia, Serbia and Ukraine.

Serbia has had the most deaths from the virus (14) while Ukraine has had a whopping 23,000 total cases.

“Following the decade’s lowest number of cases in 2016, we are seeing a dramatic increase in infections and extended outbreaks,” says Zsuzsanna Jakab, WHO regional director for Europe, in a press release.

“We call on all countries to immediately implement broad, context-appropriate measures to stop further spread of this disease,” Jakab said.

How it works: Measles is highly contagious, spreading from person to person via droplets in coughs and sneezes. One of its telltale signs is a rash consisting of flat red spots that appear on the face and spread downward to the neck, trunk, arms, legs, and feet.

The illness can be accompanied by a high fever of greater than 104°F, according to the CDC.

While most people recover from measles without complications, the virus can cause encephalitis, meningitis, pneumonia, liver infection and death.

The context: The measles, mumps and rubella vaccine, known as the MMR vaccine, prevents infection and is a major public health success story, but unverified claims that the MMR vaccine is associated with autism has led to reduced vaccination rates in Europe, parts of the U.S. and elsewhere.

Those claims can originally be traced to a study in The Lancet on a 12-person trial that tied the measles vaccine (MMR) and autism.

The study was fraudulent, and its author, Andrew Wakefield, was stripped of his medical license.

But the findings from that study still circulate widely on social media.

As a result of reduced vaccination rates, measles outbreaks have been occurring not only in Europe, but also in the U.S.

The bottom line: To prevent measles outbreaks, at least 95% of a population needs to be immunized. This is known as "herd immunity."

The WHO found that across the region, while 90% of eligible children had been immunized in 2017, this coverage is far lower at the local level. In some communities, there was less than 70% immunization coverage.

“We can stop this deadly disease. But we will not succeed unless everyone plays their part: to immunize their children, themselves, their patients, their populations — and also to remind others that vaccination saves lives."

— Zsuzsanna Jakab, WHO

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