First, there’s the simple limit to testing capacity. As things increase, our testing capacity doesn’t increase as fast, and so we’re missing more and more cases. That can give you a distorted picture — it could look like a plateau in Gauteng, but you could imagine it’s really a much higher crest…

I also bet we can expect a lot more underreporting of Omicron, compared to previous wave, because it’s more mild, either through existing immunity or through actual reduction of intrinsic severity. And if, on average, you’ve reduced the severity of cases, there’d be a lot of people that don’t bother to come to the hospital or to get tested. And so as a rough guess, you might go from like one in 10 cases reported in South Africa to one in 20 or even one in 30 cases — that wouldn’t seem unreasonable to me. And that makes it so that at the same caseload of Delta versus Omicron you could actually have three times as many infections with Omicron.

We could also have a change in generation interval. If we have Omicron kind of doubling at this very fast two or three day rate, you don’t actually have to have Rt be three. You could have actually just made the whole thing faster without having the number of secondary infections being much higher. And we don’t have no way of knowing that at this moment.

The last two are, it might not be that the entire population is susceptible to Omicron. Maybe half the population is susceptible. And then, finally, I think there’s a network effect—that as things kind of percolate through the community, you can imagine those transmission chains circling back on themselves and hitting someone that has already been exposed.