Trump is once again at odds with his top medical appointees.

The Centers for Disease Control and Prevention drafted a sweeping order last month requiring all passengers and employees to wear masks on all forms of public and commercial transportation in the United States, but it was blocked by the White House, according to two federal health officials.

Most public health officials believe that wearing masks is one of the most effective ways to protect against the spread of the virus, particularly in crowded, poorly ventilated public places that attract people from all over, like transportation venues. Many feel that the Trump administration has turned the wearing — or not wearing — of masks into a political expression, as seen most dramatically on Monday evening when President Trump whipped off his surgical mask at the White House door after returning from the hospital where he was treated for Covid-19.