Scientists are seeing signals that COVID-19's alarming Omicron wave may have peaked in Britain and is about to do the same in the US, at which point cases may start dropping off dramatically.
The reason: The variant has proved so wildly contagious that it may already be running out of people to infect, just a month and a half after it was first detected in South Africa.
"It's going to come down as fast as it went up," said Ali Mokdad, a professor of health metrics sciences at the University of Washington in Seattle.
At the same time, experts warn that much is still uncertain about how the next phase of the pandemic might unfold.
The plateauing or ebbing in the two countries is not happening everywhere at the same time or at the same pace. And weeks or months of misery still lie ahead for patients and overwhelmed hospitals even if the drop-off comes to pass.
"There are still a lot of people who will get infected as we descend the slope on the backside," said Lauren Ancel Meyers, director of the University of Texas COVID-19 Modeling Consortium, which predicts that reported cases will peak within the week.
The University of Washington's own highly influential model projects that the number of daily reported cases in the US will crest at 1.2 million by January 19 and will then fall sharply "simply because everybody who could be infected will be infected," according to Mokdad.
In fact, he said, by the university's complex calculations, the true number of new daily infections in the US -- an estimate that includes people who were never tested -- has already peaked, hitting 6 million on January 6.
In Britain, meanwhile, new COVID-19 cases dropped to about 140,000 a day in the last week, after skyrocketing to more than 200,000 a day earlier this month, according to government data.
Numbers from the UK's National Health Service this week show coronavirus hospital admissions for adults have begun to fall, with infections dropping in all age groups.
Kevin McConway, a retired professor of applied statistics at Britain's Open University, said that while COVID-19 cases are still rising in places such as southwest England and the West Midlands, the outbreak may have peaked in London.
The figures have raised hopes that the two countries are about to undergo something similar to what happened in South Africa, where in the span of about a month the wave crested at record highs and then fell significantly.
Still, the sheer numbers of people infected could prove overwhelming to fragile health systems, said Dr. Prabhat Jha of the Centre for Global Health Research at St. Michael's Hospital in Toronto.
"The next few weeks are going to be brutal because in absolute numbers, there are so many people being infected that it will spill over into ICUs," Jha said.
Omicron could one day be seen as a turning point in the pandemic, said Meyers, at the University of Texas.
Immunity gained from all the new infections, along with new drugs and continued vaccination, could render the coronavirus something with which we can more easily coexist.
"At some point, we'll be able to draw a line -- and Omicron may be that point -- where we transition from what is a catastrophic global threat to something that's a much more manageable disease."
That's one plausible future, she said, but there is also the possibility of a new variant -- one that is far worse than Omicron -- arising.