WATCH: Trump's NIH director says he is 'puzzled and disheartened' by president's mask-free Michigan rally
Des Moines, IA / USA - 01/30/2020: Enthusiastic Trump supporters waiting for the arrival of President Donald J. Trump on Thursday 01/30/2020 at his Keep America Great rally in Des Moines, Iowa.

Francis Collins, the director of the National Institutes of Health, told a CNN town hall this week that he was "disheartened" to see President Donald Trump holding a campaign rally in Michigan in which few attendees wore face masks during the COVID-19 pandemic.

As Politico reports, Collins delivered a blunt criticism of the president's rally when he was asked about it on Thursday night.

"Imagine you were an alien who landed on planet Earth, and you saw that our planet was afflicted by an infectious disease and that masks were an effective way to prevent the spread," he said. "And yet, when you went around, you saw some people not wearing them and some people wearing them. And you tried to figure out why, and it turned out it was their political party."

Collins went on to say that, as a scientist, he was "pretty puzzled and rather disheartened" to see no one wearing masks at the Trump rally.

Watch the video below.