(CNN) - According to the World Health Organization, the biggest health threats in 2019 include HIV, Ebola, and climate change.
There's also a surprising new threat on this year's list: vaccine hesitancy.
The news comes amid new outbreaks of measles in the US, including 170 cases reported since September in New York alone.
The WHO says the disease rose by 30 percent globally between 2016 and 2017.
There are many reasons people might not get vaccinated, but vaccine hesitancy is defined as reluctance or refusal to vaccinate despite the availability of vaccines.
Measles is far from the only disease threat the anti-vax movement is helping strengthen.
Propaganda against the human papilloma-virus vaccine could limit how many new cases of cervical and other cancers it prevents.
The WHO also reports less than 30 cases of another disease that can be prevented by a vaccine were seen in the world last year: polio.
Those occurred in Afghanistan and Pakistan.
The organization hopes to see the crippling disease wiped out for good this year.