Cummins-2020-09-08

This is a response to a widely-circulated YouTube video by Ivor Cummins in which he claims that Covid-19 is essentially all over, and that we've been lied to. His manner is persuasive with a kind of hypnotic lilt, carrying the air of the reasonable man wearily dismantling the establishment. His message is seductive because we'd all like to believe the pandemic is nothing to be worried about and we'd also all like to believe we have one over on the establishment who lack the perspective that we naturally possess (or who have some kind of malign ulterior motives that he alludes to). Despite the fact that almost everything in the video is, I believe, completely wrong, I was actually struck by the persuasiveness of the presentation, and given how many views his video has (more than 1.2 million at the time of writing) I thought it was worth spending some time investigating its claims.

Since I'm a mathematician, this will focus on the more mathematical aspects of the video. For a good critique that goes into some medical details, you can read this by Dr Dominic Pimenta.

These are some of the main claims Ivor Cummins makes in his video.

1. In temperate countries/regions you get a universal infection curve - a rapid increase followed by a slower decrease - which he calls a Gompertz curve.
2. In such countries, he says you quickly get 20% of the country infected, with the remaining 80% having prior immunity, so the infection is therefore over after this Gompertz curve has been navigated.
3. He says the number of Covid-19 deaths is nothing special compared to previous years and the extra deaths are just people who were waiting to die anyway (the "dry tinder"), due to fewer than normal deaths occurring in the previous year, thereby leaving the frail behind.
4. He says lockdown and restrictions have little to no effect.
5. He also later says lockdown and restrictions have prevented a useful spread of the virus in summer months, which would have enabled us to build immunity. (Yes, this contradicts 2. and 4.)

Unfortunately all of this is wrong. Almost every country in the world has kept a lid on the disease, to a greater or lesser extent, by lockdowns or distancing and no country has seen a substantial portion of their population infected thus far. There is therefore a large potential for more deaths if distancing measures are relaxed too far.

It's also not true that there has been substantially less than the normal amount of mortality in recent years. His graphs purporting to show this are largely smoke and mirrors. Any such "dry tinder" (mortality displacement) effect is very small at best, and possibly entirely non-existent.

In detail:

1. The Gompertz Curve

The Gompertz curve ("the classic Gompertz curve" as Cummins is fond of saying) is a fiction of Prof Michael Levitt, the Nobel prize-winning chemist Cummins refers to at 0:50 into his video for his inspiration. To be clear, there is such a thing as a Gompertz curve, but there's no reason to believe that it fits the trajectory of the various Covid-19 epidemics around the world, and every reason to believe it doesn't. It's just numerology. (In fact Cummins mistakes the Gompertz curve, which is always increasing, for its derivative, but let's leave that aside.) In March and April Levitt simply fitted Gompertz curves to the existing epidemic curves around the world and extrapolated them into the future to get a prediction. Of course with three parameters to vary, and the general shape of a steep upslope followed by a slower downslope, you are likely to be able to get a fair visual fit to rather rough data if you fit these parameters afterwards, but this is about as enlightening as the brontosaurus theory of A. Elk (Miss) ("thin at one end, much, much thicker in the middle, and then thin again at the far end").

How have his predictions fared? With China he got lucky and predicted something close to (what China says is) the number of final deaths. With other countries his predictions didn't work out so well. In Israel, Levitt said there would only be 10 deaths in total from Covid-19, based on his Gompertz curve. As of today (19 September 2020) there have been 1196 deaths in Israel, with 27 new deaths announced yesterday. Israel is now fully in the grip of a second wave.

On 25 July, Levitt predicted that the US would have 170k total Covid-19 deaths, which was 42k more deaths than there were on the date of his prediction. He also said the outbreak would be over in 4 weeks in the US. As of 19 Septemeber, 8 weeks after his prediction, there have been 75k more deaths and the disease is unfortunately still going strong.

How did Levitt respond to these failures of his predictions? He did at least admit he was wrong, though he was pretty ungracious and minimised it as you can see here, though of course that article was from the 28 August when the true scale of his wrongness was yet to make itself clear. See how he makes definite statements about what will happen without a hint of uncertainty. Such statements from such a high profile scientists have the potential to be used by Ivor Cumminses the world over and cause carnage. Yet when Levitt is proved wrong he just shrugs and says "oops", or to give you the exact quote "It was probably wrong of me to say that lockdown was a mistake. If people have done it, they should be told that it was probably a good idea when they did it, but it’s no longer necessary and there’s nothing left to be frightened of." a half-hearted apology with more disinformation tacked on the end.

The fundamental point is that to the extent that the Gompertz curve fits the data at all, it is fitting the effect of the social response to the outbreak, not the natural trajectory of an unchecked outbreak. Ivor Cummins is making exactly the same mistake. This curve works to an extent so long as the the distancing (etc) measures play ball with it. But it's completely wrong to assume the infection is done when we're at the bottom of the curve. If distancing is relaxed enough the infection will certainly be back.