LONDON — Now that Prime Minister Boris Johnson has become the first head of government to test positive for coronavirus, he will have to change the way he operates as he seeks to lead his country through the crisis. Other leaders — it is inevitable he will not be the last to have to self-isolate and “work from home” — will be interested to see how he adapts to what will be a very strange working environment for someone used to a steady flow of meetings, able to summon advisers into his presence at will.

However, it is also a good opportunity to take stock of his crisis management style, including the way he communicates to the public. Mr. Johnson has shown in his rise that he can be a very effective communicator. But the style — deliberately bumbling and disheveled; fond of jokes; disregarding facts and details in favor of bluster — does not lend itself to a crisis as grave as this.

As someone who has known Mr. Johnson for several decades, and never hidden my view that he is not fit to be prime minister, I do not imagine he will listen to any advice I give.

But I am nonetheless offering it, that he should use his isolation to develop a new way of communicating: more fact, more detail; less rhetoric, less bluster; cut the homilies and rambles; fewer snappy one-liners; more empathy for the dead and dying, and those caring for them; more explanation of decision making; more linking of new policy announcements to previous ones, and to data; use of graphics and film to explain; and, please, comb your hair! This is not a trivial point. In times of crisis, people look to leaders for confidence and strength. If you look disorganized, people fear that you are disorganized.