After surging for months because of the hypercontagious Delta variant, COVID-19 cases in the United Kingdom are rapidly plummeting, raising the question of whether America’s Delta wave could also peak sooner than expected.
“In the United Kingdom … cases are clearly coming down at this point,” Dr. Scott Gottlieb, the former Food and Drug Administration commissioner, told CNBC on Monday. “If the U.K. is turning the corner, it’s a pretty good indication that maybe we’re further into this than we think, and maybe we’re two or three weeks away from starting to see our own plateau here in the United States.”
The U.K.’s turnaround has been startling in its abruptness and speed. Last week, the leading British COVID modeler told the BBC that the country was “almost certain” to hit 100,000 cases per day — a number that could soar, he added, to 200,000 by the end of summer. U.K. Health Secretary Sajid Javid made a similar prediction.
Around the same time, the U.K.’s daily case count crossed the 50,000 threshold for the first time since January, and more cases seemed inevitable.
But ever since July 20, the opposite has happened: Cases have fallen for seven straight days, and they have fallen fast. From a high of nearly 54,000 on July 17, the daily tally slid to 43,404 last Wednesday; 39,315 on Thursday; 35,654 on Friday; 31,285 on Saturday and 28,652 on Sunday.
This Monday, the U.K.’s case count slipped below 25,000 — a 50 percent reduction in a single week. It fell further on Tuesday before rising slightly on Wednesday (though to a level still 36 percent below last Wednesday’s mark).
Since it’s premature to offer definitive answers, experts are wary of over-interpreting this steep and unexpected decline — assuming it continues. The U.K. repealed its last remaining COVID restrictions on July 19, and experts warn that unmasked young Britons crowding back into nightclubs could theoretically undo any progress the country has made.
Despite this, the U.K.’s drop in COVID cases could be an encouraging sign for Americans who can’t wait to turn the corner on Delta.
So what’s happening?
A number of things all at once, potentially. Some experts have theorized, as the BBC’s health and science correspondent James Gallagher recently explained, that the European soccer championships, held June 11 to July 11, led to a spike in cases due to people watching the football in crowded pubs and homes — that subsided after the tournament ended. Others have speculated that the start of the U.K.’s summer school holiday around July 20 has reduced the spread among children and parents.
Proponents of this theory point to the fact that Scotland ended its school year weeks earlier than England and was eliminated from the Euros weeks earlier as well. They say that may be why COVID cases started falling in Scotland on July 2 — again, weeks before cases started their decline throughout the U.K. The fact that Scottish cases have continued to plummet ever since — and that hospitalizations, a crucial indicator, have followed suit — may suggest that the rest of the U.K. is not far behind.
Another intriguing data point comes from the Office for National Statistics, which recently estimated that 92 percent of adults in England and Wales have antibodies to SARS-CoV-2 through vaccination or previous infection; the numbers were similar in Northern Ireland and Scotland. The implication here is that after rapidly tearing through the unprotected population — something it does with greater efficiency than any previous variant — Delta is suddenly finding it more and more difficult to spread because so many people have acquired one form of immunity or another.
“We still have enough non-immune people around” — especially minors — “to reverse this trend if we completely stop trying to avoid spreading the infection,” Adam Finn, professor of pediatrics at Bristol University, recently told Financial Times. “But with every passing day another cohort of people, recently immunised, is added to our protection alongside those who have recently had the infection, survived and recovered.”
Scientists have dismissed the idea that the U.K. has achieved herd immunity (a.k.a., the point at which the virus can’t find new hosts because so many people have antibodies).
“‘Running out of people to infect’ gives you much more rounded peaks,” health economist Zoe McLaren noted on Twitter. “The pointy peak implies a much bigger role for behavior change. Skyrocketing cases get people’s attention and R” — the number of additional people each infected person passes the virus to — “comes crashing down.”
It’s possible, however, that ever-increasing immunity is helping to amplify the impact of behavioral changes, and that some novel combination of the two may be driving Delta’s U.K. free fall. Improving weather tends to mean more outdoor gatherings; rising awareness and alarm tends to trigger more caution at the margins.
The result may be a new kind of virtuous cycle. Mass vaccination builds a big foundation of immunity. Delta rapidly adds lots of new “natural immunity,” especially now that many people aren’t masking and distancing anymore. And together they could lower the bar for reversing a wave.
“It has taken two full and draconian lockdowns to bring surging cases under control in the past,” the BBC’s Gallagher wrote this week. “But it is possible that sufficient immunity has put us into a place where the small things make the difference between cases going up or down.”
For those watching from the U.S. — where Delta is now propelling cases and hospitalizations to their highest levels in months — the U.K. U-turn is enough to inspire both envy and hope.
No two nations are exactly alike when it comes to COVID. But the U.S. and the U.K. have some important similarities. Both experienced several massive waves of infection prior to Delta, and both have the antibodies to show for it. Both have fully vaccinated a significant share of their population: 56 percent in the U.K., 49 percent in the U.S. (After initially delaying second shots, the U.K. has administered at least one dose to far more of its residents than the U.S. — 70 percent vs. 56 percent — but studies show that a single dose doesn’t provide a lot of protection against Delta.) And America’s curve of reported cases is now rising at the same steep angle as the U.K.’s just before it unexpectedly turned around.
There is, however, one key difference between the U.S. and the U.K. America’s current per capita case rate (18 reported cases for every 100,000 residents as of July 27) is identical to the U.K.’s on June 25 — which suggests that we may be lagging about a month behind our overseas counterparts and that our case counts could nearly quadruple, like theirs did, before coming down again. But one month ago, the U.K. was testing a staggering eight times as many of its people as we were, relative to population — and today they’re testing at roughly 10 times our rate.
This lack of testing could be concealing how far and wide the Delta wave has already spread in the U.S., according to Gottlieb, and skewing our sense of how much longer it might take for it to peak.
“I believe that there is more virus than we're picking up right now,” the former FDA commissioner told CBS on Sunday. “There's probably a lot of people with mild to subclinical infection since more of the infection is happening in a younger population that's less likely to become very symptomatic.”
“We’re not doing a lot of testing [and] more of the testing that we are doing is antigen tests that are being done at home and not getting reported,” he continued. “So, I think we’re much further into this epidemic than we’re picking up — and hopefully further through this epidemic.”
Hospitalization rates hint that Gottlieb’s hypothesis might be correct. At the moment, the U.K. is still recording more than two-and-half times as many daily cases as the U.S., relative to population. But more people (per capita) are actually hospitalized with COVID in the U.S. than in the U.K.: About 8.9 patients per 100,000 residents here compared to about 7.7 per 100,000 over there. One way to explain this discrepancy is that the U.K. is simply detecting a far greater share of their infections than the U.S.
There are other explanations, of course. The U.K. has fully vaccinated more than 90 percent of its seniors (i.e., the people who are most vulnerable to hospitalization); the U.S. rate is closer to 80 percent. Likewise, vaccine uptake in the U.S. is far more polarized by politics and geography than in the U.K. — which means that the Delta variant might have a lot more room left to rip through undervaccinated communities throughout America before hitting whatever mysterious tipping point it’s now hitting, simultaneously, across every single region of England.
And so it’s possible that Delta’s eventual demise in the U.S. will look different than it does in the U.K. A sudden reversal could happen in places with U.K.-like vaccination rates (such as New England), coupled with longer, higher surges in less vaccinated swaths of the country (such as the South). Overall cases could plateau as different regions spike, just like last summer.
Or Delta could turn on a dime the way it did in India and the way it now seems to be turning in the Netherlands. No one knows how long it will take for Delta to peak in the U.S. But the news this week from the U.K. provides at least some cause for cautious optimism.
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