Federal health officials have been instructed to temporarily stop any “external communications” to the public, according to two officials with knowledge of the situation.

The Centers for Disease Control and Prevention is going dark, along with other federal agencies within the umbrella of the U.S. Department of Health and Human Services. This week, the returning Trump administration told these agencies to stop talking to the public—for how long, no one knows.

The administration of U.S. President Donald Trump has instructed federal health agencies to pause all external communications, such as health advisories, weekly scientific reports, updates to websites and social media posts,