A proud anti-vaxxer “fired a shot” at a woman who mocked her entire movement, but people think she’s the one who needs to get the shots.

Everything started when Autumn Dayss posted a picture of her last-minute Halloween costume idea. It featured a tiny skeleton in a baby carrier, with a caption that read “Going to a costume party tonight as Karen and her non-vaccinated child.” The post went viral, accumulating over 36K reactions and 124K shares. It also triggered a few anti-vaxxers, including Heather Simpson.

As a response, Simpson uploaded a photo with her entire body covered in red dots. “Was trying to think of the least scary thing I could be for Halloween,” she wrote. “So I became the measles.”

This woman made fun of anti-vaxxer beliefs with her Halloween costume:

The costume triggered this anti-vaxxer and she made sure to respond:

To give you some background, measles is a highly contagious viral infection that frequently causes a severe flu-like illness accompanied by a rash. According to the Infectious Diseases Society of America (IDSA), complications occur in 3 in 10 who get measles and young children are especially vulnerable. “Ear infections and diarrhea are most common, but 1 in 20 will get pneumonia,” the organization wrote. “1 in 1,000 will have brain swelling that can cause deafness and intellectual disability, and 1 or 2 in 1,000 will die.

Before the vaccine was available in 1963, nearly every child got measles by the time they were 15 years old. “The disease sickened 3 to 4 million people and led to about 500 deaths and 48,000 hospitalizations every year.”

She received many comments critiquing her costume choice and this medical professional stood out:

Lots of other people shamed her with their comments:

Later, she posted this ‘apology’ that triggered people even more:

She says she’s proud to be anti-vaxx: