What the latest science says about how — and when — the Omicron surge will end
When the ultramutated Omicron variant first surfaced in South Africa about seven weeks ago, scientists knew it would be unlike any of its coronavirus predecessors.
But beyond that, they didn’t know much — about its transmissibility, its severity, its ability to dodge our immune defenses or what kind of new havoc it might wreak as a result.
So they kept repeating the same mantra: We don’t know yet.
Now, after nearly two months of lab studies and real-world observations, those same experts have a much clearer picture of what Omicron is — and isn’t — capable of.
Some of the news is good. Some is not.
“Omicron is the most transmissible variant of all, probably four times more transmissible than Delta,” Dr. Monica Gandhi, a physician and infectious disease expert at the University of California, San Francisco, told Yahoo News. At the same time, “in this position of being in January 2022, having so much more immunity in the world, we are seeing much more mild disease from Omicron. ... [And] it’s likely inherently milder as well.”
All in all, it adds up to a virus that tends to be less dangerous to each person who catches it — but that will still find the vulnerable, strain the hospital system and upend work, school and commerce because so many more people are catching and spreading it than ever before.
The U.S. has already reported more than a million new cases in a single day, a previously unimaginable level of transmission. If admissions continue at their current pace, more Americans will be hospitalized with COVID by mid-January than at any point since the start of the pandemic.
For readers who might have checked out over the holidays, here’s a cheat sheet on what we’ve learned about Omicron in recent days — including how bad this latest, largest surge could get, and how (and when) it might end.
Omicron is less severe than Delta
This was the hope when reports of milder symptoms and quicker recoveries started trickling out of South African hospitals. Now it’s been all but confirmed.
During the first month of the Omicron-driven fourth wave in South Africa’s Gauteng province, only about 5 percent of cases were admitted to the hospital, according to a preprint study posted to the Lancet on Dec. 29, down from about 14 percent during the same province’s previous, Delta-driven wave. And just 29 percent of those admissions were for severe disease, down from 67 percent before.
The study’s authors concluded that patients admitted to the hospital during the Omicron surge were 73 percent less likely to have severe disease than patients admitted during its Delta surge.
A second study out of the U.K., published by its Health Security Agency on Dec. 31, corroborated that conclusion, finding that people there who had contracted Omicron were about half as likely to need hospital care as those infected with Delta (and about one-third as likely to need emergency care). According to Dr. Eric Topol, founder of the Scripps Translational Institute and a leading COVID expert, that implies a “60 to 70 percent ... reduction in Omicron clinical severity vs. Delta.”
The latest reports from London show this pattern playing out in real life. “Despite steep rises in cases and patients, the number on ventilators has barely risen,” tweeted Financial Times data journalist John Burn-Murdoch on Tuesday. Meanwhile, “the number of people in London ICUs has fallen in recent weeks, and is not following the same path as last winter.”
Likewise, a new report found that fewer than 15 percent of early Omicron patients in the Houston Methodist health care system had to be hospitalized, compared with 43 percent of the system’s early Delta patients and 55 percent of its early Alpha patients.
“The link between cases and severe disease,” concluded Burn-Murdoch, “has significantly weakened with Omicron.”
Why is Omicron less severe? Likely because it’s worse at infecting the lungs.
While it’s clear Omicron is less likely than Delta to make people who test positive really sick, it’s much less clear how much of this is because more people now have some degree of immunity (through vaccination or prior infection) and how much is because the new variant is intrinsically less severe than the older one.
Immunity is definitely playing a part, according to experts. But now they think Omicron is, too.
As of Tuesday, seven separate studies — in mice, hamsters and human tissue — have all shown the same thing: decreased lung-cell “infectivity” for Omicron.
In lay terms, that simply means the new variant doesn’t take hold or grow in the lungs as easily as older variants, possibly because its many mutations make it harder for a special protein on the surface of lung cells to latch onto it. One study found that Omicron levels in the lungs were one-tenth or less the level of other variants.
That’s crucial because the lungs are where COVID can transform from a mostly unpleasant infection to a life-threatening illness.
At the same time, preliminary research has also shown that Omicron might grow faster in the upper respiratory system — the nose, the mouth, the throat, the windpipe, the bronchi — than Delta or the original coronavirus.
This has led some scientists, such as Ravindra Gupta, a virologist at the University of Cambridge, to speculate that Omicron has evolved into an upper-airway specialist, thriving in the throat and nose in order to increase its chances of getting expelled into the air and infecting new hosts.
“It’s all about what happens in the upper airway for it to transmit, right?” Gupta recently told the New York Times. “It’s not really what happens down below in the lungs, where the severe disease stuff happens. So you can understand why the virus has evolved in this way.”
The good news: Vaccines still work really, really well to prevent severe disease, hospitalization and death (even if they’re less effective against infection and transmission).
Because of its mutations, Omicron is very skilled at sidestepping our immune system’s first line of defense — neutralizing antibodies — and causing infections. This is true regardless of whether you had a previous infection, one shot of Johnson & Johnson or two shots of an mRNA vaccine such as Moderna or Pfizer. One study estimated that two mRNA doses are now less than 30 percent effective at preventing an Omicron infection — protection that further wanes over time.
A third booster dose helps here because it almost immediately increases neutralizing antibodies 20- to 40-fold; reports from both South Africa and the U.K. suggest that boosters are about 70 percent effective against symptomatic infection, at least at first.
But that protection will likely wear off as well, which is why countries such as Israel are already administering fourth doses to seniors, health workers and immunocompromised patients.
What is much less likely to fade is the strong protection the existing vaccines provide against severe disease.
Even without a third shot, a new U.K. report shows the vaccines are still 52 percent effective against hospitalization. With a booster, that protection rises to 88 percent.
Why? In a Wednesday Substack post, Topol explained that once primed by vaccination or prior infection, our backup immune defenses — T cells and B cells — are astoundingly good at recognizing and combating Omicron after it triggers an infection but before it can cause severe disease.
In the past week alone, Topol writes, six new studies have come out showing “fairly well preserved T cell function ... that is durable versus Omicron 6 to 8 months out from vaccination (many types including Pfizer, Moderna, Astra-Zeneca, Novavax, J&J) and, in a few of these reports, after prior infection.”
Meanwhile, the latest research also shows that a third booster shot prompts our memory B cells — cells that remember the virus or bacteria they just fought and live in the body for a long time — to adapt with a subset that reacts specifically to Omicron.
Real-world data show how protective vaccination — and particularly boosting — can be. Over the last month, 75 percent of ICU patients in the University of Maryland medical system were unvaccinated. Twenty-two percent were vaccinated with two doses; many of them were likely immunocompromised or vaccinated more than six months ago.
Just 3 percent were boosted.
It’s worth pausing to appreciate how remarkable this is.
The bad news: Omicron is causing an absolutely astronomical number of cases.
If everyone on Earth were boosted, Omicron would have a tougher time spreading. But just 22 percent of Americans have received a third jab, and 40 percent of the world’s population hasn’t even gotten their first.
The result: case counts that seemed unthinkable just weeks ago.
In the U.S., Omicron accounted for just 8 percent of cases on Dec. 11. A week later, that number had skyrocketed to 38 percent, and by Christmas it had doubled to 77 percent. Now, roughly a month after the variant was first detected here, more than 95 percent of U.S. cases are Omicron, according to the Centers for Disease Control and Prevention. By comparison, it took Delta four months to clear the 50 percent threshold.
Earlier this week, one Spanish physician and medical historian described Omicron as “the most-explosive and the fastest-spreading virus in history.” Harvard epidemiologist William Hanage echoed that assessment, calling it “the most rapidly spreading virus among the ones we have been able to investigate at this level of detail.”
The latest numbers from the U.S. and elsewhere certainly bear that out. Before Omicron, the most new U.S. cases recorded in a single day were 300,777 on Jan. 8, 2021. On Monday, the U.S. recorded 1,018,935 — more than three times as many.
Previously, America’s highest seven-day average was 251,232. Now it’s 547,613 — and it shows no sign of slowing down.
Worldwide, the total daily case count cleared 900,000 exactly twice before, in April 2021. It never came close to crossing the 1 million mark.
The latest number of global cases, from Jan. 4? More than 2.6 million.
So while individual Omicron infections might be less severe, on average, the sheer volume of them is still causing huge problems at hospitals, schools and elsewhere.
More than 114,000 Americans are currently hospitalized with COVID-19 — a number that has risen 51 percent over the last two weeks.
To put that in perspective, the hospitalization peak during America’s deadly recent Delta wave was about 105,000 COVID patients. At no point during the spring or summer of 2020 — long before the advent of COVID vaccines — were more than 75,000 Americans ever hospitalized with COVID.
The all-time peak for U.S. COVID hospitalizations came on Jan. 14, 2021: 142,315. At the current rate, we’re likely to pass that peak about a week from now, setting a grim new U.S. hospitalization record. Given the lag between cases and admissions, the number of COVID hospitalizations in the U.S. will probably keep climbing from there.
Already, hospitalizations in hot spots like New York and Florida — which will likely serve as bellwethers for the rest of the country — are increasing at much faster rates than in places where Omicron has yet to take off: 110 percent and 264 percent over the last two weeks, respectively. More people are already hospitalized with COVID in New York, New Jersey, Washington, D.C., Maryland, Delaware and Connecticut than during last winter’s peak.
As many have pointed out, this current wave of Omicron hospitalizations is different from previous waves, with a lower percentage of patients on ventilators or in the ICU and a higher percentage who arrive because of other ailments but then “incidentally” test positive for COVID upon screening.
But an average of 1,300 Americans are still dying of COVID each day, a number that has essentially held steady since Halloween. Meanwhile, the massive influx of patients arriving at the hospital either for COVID or with COVID — an influx that will only get worse in the weeks ahead — is stretching the system to its breaking point.
According to health researcher Benjy Renton, 505 U.S. counties are currently projected to be at hospital capacity (up from 322 the day before); an additional 541 counties are at high risk of hitting capacity within the next 10 days (up from 456 the previous day); and 275 counties have already reached an “unsustainable” level of pressure. All told, an estimated 80 percent of the U.S. population now lives in counties that have either exceeded their hospital capacity or risk doing so soon.
Doctors have increasingly taken to Twitter and other platforms to explain why this is such a problem:
“Now record-number COVID cases are hitting at a time when our ERs are already seeing extremely high numbers of non-COVID patients too. Thankfully the COVID patients aren’t as sick. BUT there’s SO many of them,” tweeted New York emergency physician Craig Spencer. “Like before, there were some really short of breath and needing oxygen. But for most, COVID seemed to topple a delicate balance of an underlying illness. It’s making people really sick in a different way.
“Diabetics in whom COVID precipitated diabetic ketoacidosis, a serious and life-threatening condition,” Spencer continued. “Older folks sick with COVID just too weak to get out of bed. Can’t walk. So can’t leave the hospital. ... What’s also different now is those COVID cases are often in beds next to patients who’ve done everything to avoid the virus, and for whom an infection might have a dramatic toll. The cancer patient on chemotherapy. Those immunocompromised or severely sick with something else.”
“The next few weeks will be really really tough for us,” Spencer concluded. “A lot of health care workers will get sick. We will have to work short-staffed and take on more patients. I know you’re tired of this. We are too. But we’ll really need everyone’s help to get through it, again.”
In the U.K., for instance, Omicron was associated last week with the “absence (sick or isolating) of ~68,000 healthcare professionals, representing 5% of the workforce.”
Similar dynamics are also affecting schools — thousands which are delaying opening or going remote because so many teachers and students are testing positive — as well as firefighters, police, airlines and other businesses.
It’s important to note that an individual case of Omicron is less likely to kill or hospitalize that individual. But in a society where nearly everyone still agrees that such individuals should isolate to avoid wantonly spreading the virus to others who might be more vulnerable, adding another million new cases each day to the national burden is bound to have some very disruptive — and in many instances dangerous — ripple effects.
Fortunately, Omicron might be over soon — and that could finally end the emergency phase of the U.S. pandemic, once and for all.
Right now, Omicron’s speed is a big problem. But soon it might become a good thing.
In South Africa’s Gauteng province, the Omicron wave peaked one month after it started; today, one month later, it’s basically over.
That’s incredibly fast. South Africa’s previous Delta wave lasted about twice as long.
A similar pattern may be playing out in both New York City and London, the first two global hubs to get slammed by Omicron.
“Reports of new cases in London have been plateauing, and admissions to the city’s hospitals have been slowing, according to official tallies,” the Washington Post reported Tuesday. “While admissions were growing by as much as 15 percent a day in late December, they dropped to 5 percent increases over the New Year’s weekend, and are now growing at just 1 and 2 percent.”
As for Manhattan, the number of cases reported on Jan. 3 (5,344) was slightly lower than the number of cases reported one week earlier, on Dec. 27 (5,372) — as was the percentage of tests coming back positive (15.1 percent vs. 17.5 percent).
Holiday reporting delays may be depressing case counts somewhat; holiday transmission could trigger further upticks. Still, it seems likely that whenever the actual Omicron peak arrives, it will come quicker than it did for other variants — and then plummet more precipitously.
This is a particularly welcome development because a new laboratory study carried out by South African scientists has shown that while antibodies produced after a Delta infection offered little protection against Omicron, antibodies produced after an Omicron infection are effective against Delta too.
“Omicron is likely to push Delta out,” virologist Alex Sigal, who led the new study, told the New York Times. “Maybe pushing Delta out is actually a good thing, and we’re looking at something we can live with more easily and that will disrupt us less than the previous variants.”
The upshot, as Bob Wachter, chair of the department of medicine at the University of California, San Francisco, recently predicted, is that “by early February, we could be in a place where COVID is, in fact, ‘like the flu’ — with the vast majority of the U.S. protected through vaccines or recent infections ... and a healthcare system no longer stressed to the point of perilousness, for both COVID patients & others needing our services.”
“At that point,” Wachter continued, ‘I’m over this!’ might no longer be a sign of exhaustion, confusion, or political affiliation, but rather a perfectly rational and evidence-based way of approaching COVID, and life. Fingers crossed.”