Aug. 29 (UPI) -- American nurses are expressing serious concerns over the changes at the Centers for Disease Control and Prevention, said the American Nurses Association.

The White House on Thursday named Jim O'Neill, a close ally of top health official Robert F. Kennedy Jr., to serve as acting director of the CDC, according to sources in multiple media reports.

The move came one day after the President Donald Trump administration fired CDC Director Susan Monarez less than one month into the job. Kennedy, secretary of Health and Human Services, had pushed Monarez to resign after she disagreed with his anti-vaccine policies, but she refused.

Four other CDC leaders also resigned Wednesday over frustration about anti-vaccine policy pushed by Kennedy.

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