White House communications director Alyssa Farah declined to tell reporters when President Trump last tested negative for COVID-19 on Thursday, marking at least the eighth time since last week that White House officials have refused to disclose the information.

Why it matters: One week after Trump revealed he tested positive for the virus, the White House still refuses to say when Trump's last negative coronavirus test was. The detail could help determine when he contracted the virus, who he exposed and the timeline of his illness.

The big picture: The White House is scrambling to respond to the outbreak as the list of officials who have tested positive for the virus — which includes senior officials like Stephen Miller and Hope Hicks — continues to grow.

• Several members of the White House press corps have tested positive and many are trying to figure out whether they and their families need to quarantine, Axios' Sara Fischer reports.

What's new: The Washington, D.C. Department of Health on Thursday asked attendees and White House staff at the Rose Garden celebration for the introduction of Supreme Court nominee Amy Coney Barrett on Sept. 26 to seek medical advice and get tested for COVID-19 by their local health department.

• Several people who attended the event later tested positive for the virus, including former New Jersey Gov. Chris Christie and Sens. Thom Tillis (R-N.C.) and Mike Lee (R-Utah).

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