'Read the books!' Trump tells baffled reporter of 'manuals' that advise against testing 'too much' for COVID-19

President Donald Trump left a reporter baffled recently when he told him about unspecified medical "manuals" that advise against excessive testing for the novel coronavirus.

In a set of brief preview clips of an upcoming interview set to air on HBO Monday, Trump can be seen telling Axios reporter Jonathan Swan about the perils of mass testing for the disease.

"You know, there are those that say you can test too much, you do know that," the president told Swan, who had a look of bewilderment on his face.

"Who says that?" Swan asks.

"Well, just read the manuals," the president replies.

"Manuals?" Swan asks. "What manuals?"

"Read the books," Trump insists. "Read the books!"

"What books?" an increasingly incredulous Swan asks.

Watch the video below.