UK model: There’s no evidence yet that Omicron is inherently milder than Delta

I’m, uh, reasonably sure there is evidence. Some of it is statistical, some is biological. None of it is conclusive, but it’s there in plain sight if you care to look for it.

In fact, even this study from the UK’s Imperial College of domestic cases concedes that “hospitalisation data remains very limited at this time.” So far, the share of people with Omicron who are seeking hospital care isn’t meaningfully different from the share with Delta who have sought it. But you know what can happen when a survey relies on a small sample size.

And besides, emphasizing that there’s “no evidence” to support a conclusion is … problematic in communicating about science.

Even so, the Imperial study is worth flagging as a reminder that scientists are unsure whether the mild Omicron outbreak in South Africa is due to the variant being intrinsically mild or because that country’s young, healthy population with high natural immunity is better at fending it off. It could be a combination; the new hospital data showing how well even very old South Africans are doing with the variant suggests that it really is inherently milder. But is it so much milder that deaths won’t surge among an older, less fit population like Britain’s or America’s?

We’ll know in a month.

Ferguson said the data provided “no strong signal of an intrinsically reduced severity of Omicron vs Delta”, but he said a “much more definitive judgment” could be made “within a week” as more data emerge on Omicron-related admissions, which are increasing “quite sharply” in London and Manchester…

“We do really need to wait for a little bit more data on severity . . . before being definitive, the challenge with that is if we wait too long, it may be too long,” he added.

The findings on severity were based on analysis of 120,000 Delta cases and 15,000 suspected Omicron cases, which found that people infected with Omicron were no more likely to be asymptomatic than those infected with Delta.

This was supported by early evidence that Omicron infections were no less likely than Delta to result in hospitalisation, though this assessment was based on only 24 Omicron hospitalisations compared with more than 1,000 for Delta.

“Severity” can mean different things. If Delta and Omicron end up sending the same percentage of people to the ER in need of supplemental oxygen, arguably they’re equally “severe.” But if 10 percent of Delta patients in the ER die versus one percent of Omicron patients, they are … not.

Some critics are scoffing at the Imperial study because that’s the same outfit that modeled more than two million deaths from COVID in the U.S. at the start of the pandemic. “They overestimated the severity of the disease once and now they’re doing it again!” Maybe. But the early death estimate was a guess at how many would die if the U.S. did nothing to try to control COVID, which was never in the cards. And as it is, we’ve seen more than 800,000 perish with a million more saved only because of the vaccines. The seemingly outlandish worst-case scenario from Imperial College doesn’t look so outlandish in hindsight.

The projected death toll from Omicron is a black box for now but there are two other tolls that seem to be baked in and unavoidable. One is economic. “Restaurants are shutting down, colleges have axed events and several Broadway shows have been canceled,” says Axios about NYC’s reaction to the huge surge of cases. British media is chattering about a “stealth lockdown” over there as cases go vertical in London, where businesses are taking a hit not because the government ordered them to close but because too few patrons are willing to venture out as Omicron spreads. Quote: “Pubs, bars, cafés and restaurants have already seen trade fall by a third and are expecting a further 22 per cent drop in bookings for December.” Trips on the London Tube are down 20 percent in a week.

If the Omicron wave peaks quickly and falls rapidly, as it appears to be doing in South Africa, maybe the economic jolt will be brief. What if it doesn’t?

The other toll is to the health-care system. Practically every news story about the coming Omicron wave in the U.S. features a quote from some doctor or scientist emphasizing that even a mild virus can wreak havoc with hospitals if it infects enough people. And Omicron is spreading at a phenomenal rate. Watch Scott Gottlieb make the point that a small fraction of a huge number is still a big number.

One expert guesstimated that the U.S. could hit one million cases per day, which would be fully four times higher than the peak we reached over the first 22 months of the pandemic. Assume that the optimistic new numbers from South Africa hold true, that only 1.7 percent of people who test positive for Omicron need ER care. If the virus causes 10 million cases here, that’s 170,000 people who’ll land in the hospital — in short order, given how quickly the variant spreads. The most COVID patients the U.S. has ever had hospitalized at one time was 137,000 last winter.

And American hospitals are in no position to manage a new peak:

“We’re facing a national emergency,” said Rick Pollack, CEO of the American Hospital Association.

“Just think about it: when America shut down, our folks stepped up and they continued to do that,” Pollack told Axios. “And for two years now, they’ve been going absolutely full throttle.”

In Kentucky, officials say hospitals have been so overrun in recent months, there have been days hospitals haven’t had the bandwidth to help incoming patients, or even find places to transfer them.

Describing one particularly tough day, one chief medical officer in the state told Bloomberg : “Five people died that day and that’s what saved us.”

There’s another wrinkle. No one knows yet if natural immunity obtained from an Omicron infection will work against Delta or vice versa. There’s a theory that the two variants might be different enough from each other that protection from one won’t guarantee protection from the other. Why do I mention that? Because data from London shows that the explosive rise of Omicron hasn’t driven Delta to extinction yet. They might coexist in the population, which could mean hospitals will have to manage a winter Delta wave alongside an Omicron one.

Nothing to do now but wait and find out the hard way what we’re dealing with. Will a famously obese country fare as well against a virus that preys on obesity as South Africa has? Stay tuned.

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