Getting heads around exponentiality takes time. Ask the White House.

The Covid-19 penny sometimes takes a while to drop. Partly because of the inability of the human brain to easily understand the concept of exponential growth. Witness the US White House move from dismissal to denial and now near panic. Yesterday US president Donald Trump referred to "three weeks like we've never seen before" with American Covid-19 deaths now projected to reach as high as 240,000.

Here in South Africa, where we are around two weeks behind the global curve, many are also struggling with the concept, grumbling about a national lockdown when there are "only" five deaths. But for those who take the trouble to extrapolate the numbers, the warning is clear. The virus hasn't really hit SA yet. But it's coming. Soon.

The threat is clearly appreciated by Mary Slack who yesterday matched her brother Nicky Oppenheimer's donation of R1bn to the Solidarity Fund. And by Adrian Gore, an actuary, who explained an initial R20m has been set aside by Discovery and its partner Vodacom to pay doctors for 100,000 one-on-one consultations available free to Covid-19 victims. That's a lot of doctoring, but might only be the start.

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