South Bend Mayor Pete Buttigieg changed his answer to a national news organization's questions about vaccines, saying that he backed exemptions only for medical reasons after initially saying he also supported "personal belief and religious exemptions" in some instances.

The campaign's initial response drew criticism online and follows a growing number of outbreaks of vaccine-preventable diseases in Indiana and across the nation.

Buttigieg responded to three questions he and many other 2020 presidential candidates were asked by BuzzFeed News for a story that posted Tuesday night. They are:

What do you believe about vaccines? Do you believe vaccines are a possible cause of autism? Do you support efforts to end religious and personal belief exemptions, leaving only medical exemptions?

Buttigieg said exemptions are appropriate for people who can't be vaccinated for medical reasons. He also said he supports "personal/religious exemptions if states can maintain local herd immunity and there is no public health crisis."

After the story posted, the campaign changed its position on exemptions to point only to medical situations.

The original response was met with criticism on social media.

In response to questions from IndyStar about why that answer changed, a spokesman for the campaign repeated its second, narrower answer to BuzzFeed and added that the initial response “didn't accurately portray his position.”

The Buttigieg campaign's comments on vaccines come as the number of measles cases in the U.S. have reached their highest point since 1994. The U.S. Centers for Disease Control and Prevention reported Monday that there were 704 cases of measles in 22 states. Indiana is among the states with at least one confirmed case.

Health officials declared measles eliminated in the U.S. in 2000.

A recent mumps outbreak at Indiana University Bloomington also sickened 20 students as of April 22. Most of those sick students were vaccinated, an IU Health Center spokeswoman said.

Mumps at IU:Why some vaccinated students still got sick

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Measles, mumps and rubella are all prevented by the MMR vaccine. The CDC recommends children get two doses of the MMR vaccine, starting with the first dose at 12-15 months old, and the second dose between ages 4 and 6. Teens and adults should also be up-to-date on their MMR vaccination.

Two doses of the vaccine are about 97% effective at preventing measles. One dose is about 93% effective, the CDC said.

Andrew Clark is Facebook editor for IndyStar. Call him at 317-444-6484 or email him at andrew.clark@indystar.com. Follow him on Twitter @Clarky_Tweets.