As Andrew Sullivan wrote, Trump responded to the outbreak in Wuhan early, in January, by banning travel to and from China for Chinese citizens. He could have capitalised on his image as the defender of borders, protector against foreign threats, and fighter of a trade war against China.

Instead, he reversed his position, spending most of February saying the epidemic “will go away” and insisting on business as usual. Sullivan said: “He suddenly panicked that an epidemic could hurt the stock market and slow the economy in an election year.”

Now Trump is trapped by the reality of a death toll in the US that is accelerating towards China’s total, and still holding photocalls in the White House with members of his cabinet crowded behind him…

Johnson, on the other hand, resisted populist anti-foreigner measures in the early days of the outbreak, but acted quickly when the scientific advice changed. He has been criticised for being too slow to respond, but Lawrence Freedman, professor of war studies at King’s College London, has performed a public service by looking at the evidence.