One great unknown about the coronavirus pandemic circling the globe is how it will respond as the weather gets warmer.
The virus will "go away in April," U.S. President Donald Trump told a meeting of governors last month, "as the heat comes in." That over-confident assertion has attracted criticism from virologists and fact-checkers. Most respiratory diseases — such as influenza and the mundane rhinovirus and coronavirus strains that cause the common cold — do indeed spread more rapidly in the cold, dry conditions of the winter months.
But it's been impossible to say for sure how COVID-19 would behave in summer and late spring for an obvious reason — the strain didn't exist until around November last year.