When President Trump sees a political threat, his instinct is to deny, double down and hit back. That has often been politically effective, but in the case of the novel coronavirus it has undermined his ability to lead.

It’s not accurate, as the press reported last week, that the President called the virus a “hoax.” He said the criticisms of his Administration were a hoax. Yet his public remarks too often continue to give the impression that he views the virus more as another chance for political combat than as a serious public-health...