Gottlieb: Has the Delta wave already peaked?

Depends on where you look, but the hotter spots for COVID-19 transmission might have already peaked. Former FDA commissioner Scott Gottlieb predicted two weeks ago that the US could be further into the Delta wave than we know, thanks mainly to a lack of regular sample testing that has plagued the US response from the start.

That’s important context for the charts Gottlieb highlighted yesterday evening, based on data sourced from Johns Hopkins and the CDC.  Have we at least plateaued in transmissibility?

Gottlieb’s choice of graphs aren’t entirely representative, although it’s not deceptively positive either. When looking at the entire range of state data, there appears to be a number of plateaus or flat-out downward curves. Delaware, for instance, had a crazy reproduction-number curve over the past month:

That peak was 3.24, making Delaware one of the hottest spots for COVID-19 last month, followed by a dramatic collapse in transmission. Did that result from the virus burning through the not-fully-vaccinated population (around 50%) quickly? Or did it drop off because people stopped creating social-contact environments for rapid transmission? Likely it was a combination of both, which is going to make it difficult to predict whether Delaware really has passed peak-Delta wave or just behaved well enough to extend the distribution more rationally. I’d guess that it’s more the former than the latter, but as we’ll see shortly, it might be both.

Not every state demonstrates a peak, either; in fact, some appear to be just getting revved up. Indiana, Iowa, and Minnesota are still rising in R0 numbers, although nowhere near as high as Delaware last month. Nebraska’s number appears to be accelerating, as does New Hampshire’s, which is one of the highest at the moment with a 1.74 reproduction number. And South Carolina is looking particularly bad:

South Carolina’s behind the national numbers on completed vaccinations at 44.8%, but they’re not that far behind it. They have more people susceptible to infection, so a high R0 in the middle of a wave might be expected, but should it run this high? Not if Delta’s already peaking, and in South Carolina and a handful of other states, it’s still ramping up rather than declining or plateauing.

Overall, though, the dashboard does look promising, and it fits with Gottlieb’s predictions on July 23rd. With a few significant exceptions in a large country, it appears that the reproduction numbers have significantly shifted … for some reason. That’s exactly what happened in the UK, where the dramatic decline took everyone by surprise as well. The Hill took a more cautious view of these trends but still noted that people do expect the peak to come in the next two to three weeks, if not right at this moment. And that doesn’t mean the road will be smooth, either:

The COVID-19 delta variant surging through the United States could peak later this month, but experts say projections are difficult and much will depend on an unpredictable factor: human behavior. …

The U.S. in general has followed the United Kingdom in case trends with both the alpha and delta variants of the coronavirus. After skyrocketing cases in June and July, the U.K.’s case count has dropped dramatically, almost halving since its peak in late July.

Experts said the current U.K. trend shows that a sudden downturn in cases is possible in the U.S., but they said they are not confident the same will happen, citing different infection, vaccination and precaution compliance rates.

And even good news might pair up with bad news by nature:

Justin Lessler, an infectious diseases epidemiologist at the University of North Carolina’s Gillings School of Global Public Health, said so far the contagious variant has increased faster than any of their models, calling it “a little bit scary.”

“Given the rate is going up, it’s either going to peak earlier than we anticipated or peak much, much higher than we anticipated,” Lessler said. “I think probably both are going to be true.”

The best advice to give on this point is to stay tuned — and get vaccinated.