After 18 months (19, actually) we all know what a COVID case curve looks like during a surge in infection. It’s a bell curve, albeit a bit steeper than the traditional bell slope on each side. Cases increase rapidly, peak, and then mysteriously fall roughly as rapidly.

America’s two major waves each had the familiar bell shape:

The United Kingdom’s winter wave also looked like a bell, with a strange little dent in the month of December. Their ongoing wave does … not look like that, though. It doesn’t look like a “wave” at all. They seem to have plateaued at a high rate of daily cases and just stayed there:

David Leonhardt of the Times has written more than once about the unexplained two-month cycles in which COVID typically rises and falls. But that’s not what the Brits are experiencing. They’re in month four of a steady elevated surge.

What gives? Does this mean the vaccine doesn’t work?

Well, no. A look at the death curve shows that the vaccines and increasing overall population immunity are paying dividends in saving lives even if they’re not preventing infection as much as we’d like:

The UK topped out at an average of 1,250 deaths per day this past winter. Lately their high water mark has been slightly less than 150. The current case count rivals the darkest days of the pandemic but there’s no comparison when measuring fatalities.

Still, how do we explain the high number of cases in an age of mass vaccination? It turns out there are two theories, one alarming and one less so.

The less alarming theory is that Brits are “learning to live with COVID,” as the cliche goes. If the world ever had a realistic opportunity to eradicate the virus, it’s long gone. Endemic COVID is here to stay and the UK seems to be digesting that, with more people willing to resume social activities and a degree of pre-pandemic normalcy despite the high case counts.

Such is the strange new phase of Britain’s pandemic: The public has moved on, even if the virus has not. Given that Britain has been at the vanguard of so many previous coronavirus developments — from incubating variants to rolling out vaccines — experts say this could be a glimpse into the future for other countries.

“We don’t seem to care that we have these really high infection rates,” said Tim Spector, a professor of genetic epidemiology at King’s College London who has been leading a major study of Covid-19 symptoms. “It looks like we’re just accepting it now — that this is the price of freedom.”…

“There’s a feeling that finally we can breathe; we can start trying to get back what we’ve lost,” said Devi Sridhar, the head of the global public health program at the University of Edinburgh. “It’s really difficult to ask people not to mix for a prolonged period, especially if there is no solution.”

Some transmission may be due to British children returning to school, as that would explain high case counts with a low death toll. A COVID reporter for the Financial Times posted a thoughtful thread yesterday looking at the UK’s endless surge, including comparing England and Scotland, and came away with three conclusions. One: The Brits have let down their guard on masking somewhat, which may be boosting cases a little. Two: They’ve let down their guard on social distancing, which seems to be boosting cases a lot. Three: Waning immunity. The UK may have stumbled into the same sort of surge Israel endured six months after its vaccination program began, once immunity began falling off in older recipients.

And we really shouldn’t be surprised by this. In July we saw cases in Israel among double-vaxxed rise at the same rate as unvaxxed, and severe cases climb too.

Israel was about 3 months ahead of UK in vax rollout, and we’re now about 3 months on from July. pic.twitter.com/prhinzFYvP

— John Burn-Murdoch (@jburnmurdoch) October 17, 2021

Israel’s terrible fall crush of COVID finally began to abate a month ago as boosters rolled out aggressively across the population. It may be that any country that doesn’t get a jump on third doses five months after the second dose is doomed to experience a nasty surge. But that’s good news, relatively speaking. Governments have the tool they need to limit major outbreaks already on hand. Containment is simply a matter of staying on the ball and keeping the shots coming.

But if the UK’s problem is as simple as that — waning immunity plus less social distancing — shouldn’t the U.S. also be stuck in an an endless surge the way the Brits seem to be? We’re seeing waning and less social distancing too. Yet cases have declined here recently as the southeast’s wave finally ended.

The more alarming theory comes from Scott Gottlieb, who’s not normally an alarmist:

The variant has been in the UK since about July, but it has been slowly increasing in prevalence. There’s no clear indication that it’s considerably more transmissible, but we should work to more quickly characterize these and other new variants. We have the tools.

— Scott Gottlieb, MD (@ScottGottliebMD) October 17, 2021

A new variant — or rather, a new variant (AY.4) of an old variant (Delta). Gottlieb’s right that it’s exploded in the UK. Check this out:

In the U.S., AY.4 is only 12 percent of new cases by comparison. Maybe that’s why cases here have fallen nationally while in the UK they’ve stayed aloft. What if the Brits are dealing with a nasty new variant that’s destined to explode here in the next few months just as Delta did? Maybe we have an endless surge ahead of us too thanks AY.4.

Or maybe not. The problem for any new variant is that it needs to be able to out-compete Delta and Delta is already hyper-efficient. It will reach and infect a person before most other strains of the virus have had a chance. Partly because of that, some doctors who’ve looked at the UK numbers on AY.4 think it’s nothing to get too anxious about. At worst, it seems to be slightly more efficient than Delta, not a quantum leap.

So far no Delta subtype has seemed to have had much of an advantage over the others & non-Delta variants aren’t getting anywhere https://t.co/oCfqlgmHBc…

But AY.4 has developed a new mutation (S:Y145H) & that variation (AY.4+S:Y145H) has been growing here since July 2/6 pic.twitter.com/MeeIvzihS2

— Prof. Christina Pagel (@chrischirp) October 14, 2021

That was 10 days ago, so hopefully it will start showing up in COG & Sanger tracking soon.

It’s not growing anywhere near as fast as Delta did & even the *worst* case is only a very moderate advantage (maybe 10%) vs 50% that alpha had over wildtype and delta had over alpha 4/6

— Prof. Christina Pagel (@chrischirp) October 14, 2021

If it’s not AY.4 that explains the sustained UK surge and it’s not vastly different behavior patterns between us and them, what is it? Is there a greater seasonal effect here than there due to climate differences, maybe?

Speaking of sustained surges, I’ll leave you with this absurdly tragic and tragically absurd data from Russia. It’s been obvious for months that Russia has been cooking its COVID books, capping reported deaths at virtually the same number every day. For two months, completely unrealistically, deaths stood at almost exactly 800 each 24 hours; within the past month, for whatever reason, they’ve begun to creep upward and now stand at close to 1,000 per day. The country has recorded 224,000 deaths officially since the start of the pandemic but one unofficial count placed the true number at 418,000 as of August, with many thousands more since then. Per capita, they’re probably one of the few major nations in the world with a higher death toll than we have. And since only a third of Russians are fully vaccinated, it’s not going to get better soon.