Washington: Just before 7.30pm on Monday (Tuesday AEST) Deborah Birx walked to the lectern at the White House briefing room.

The physician, who is co-ordinating the Trump administration's response to the coronavirus, was there to present the latest national data on the pandemic and advise Americans about how to keep themselves safe.

But most Americans - even if they were tuned in to cable news at the time - never saw Birx speak. The daily briefing had already been going for two hours, dominated by a fiery question-and-answer session between US President Donald Trump and reporters.

By the time Birx was called upon to give her update, two of the three main cable news channels, CNN and MSNBC, had already switched back to regular programming. Only Fox News was still airing the press conference.