By MARIA CHENG and CAR­LA K. JOHN­SON | AS­SO­CI­AT­ED PRESS

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 U.S., 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 U.S. will crest at 1.2 mil­lion by Jan. 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 U.S. — an es­ti­mate that in­cludes peo­ple who were nev­er test­ed — has al­ready peaked, hit­ting 6 mil­lion on Jan. 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 U.K.’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.

“We are see­ing a def­i­nite falling-off of cas­es in the U.K., but I’d like to see them fall much fur­ther be­fore we know if what hap­pened in South Africa will hap­pen here,” said Dr. Paul Hunter, a pro­fes­sor of med­i­cine at Britain’s Uni­ver­si­ty of East An­glia.

Dr. David Hey­mann, who pre­vi­ous­ly led the World Health Or­ga­ni­za­tion’s in­fec­tious dis­eases de­part­ment, said Britain was “the clos­est to any coun­try of be­ing out of the pan­dem­ic,” adding that COVID-19 was inch­ing to­wards be­com­ing en­dem­ic.

Dif­fer­ences be­tween Britain and South Africa, in­clud­ing Britain’s old­er pop­u­la­tion and the ten­den­cy of its peo­ple to spend more time in­doors in the win­ter, could mean a bumpi­er out­break for the coun­try and oth­er na­tions like it.

On the oth­er hand, British au­thor­i­ties’ de­ci­sion to adopt min­i­mal re­stric­tions against omi­cron could en­able the virus to rip through the pop­u­la­tion and run its course much faster than it might in West­ern Eu­ro­pean coun­tries that have im­posed tougher COVID-19 con­trols, such as France, Spain and Italy.

Shabir Mah­di, dean of health sci­ences at South Africa’s Uni­ver­si­ty of Wit­wa­ter­srand, said Eu­ro­pean coun­tries that im­pose lock­downs won’t nec­es­sar­i­ly come through the omi­cron wave with few­er in­fec­tions; the cas­es may just be spread out over a longer pe­ri­od of time.

On Tues­day, the World Health Or­ga­ni­za­tion said there have been 7 mil­lion new COVID-19 cas­es across Eu­rope in the past week, call­ing it a “tidal wave sweep­ing across the re­gion.” WHO cit­ed mod­el­ing from Mok­dad’s group that pre­dicts half of Eu­rope’s pop­u­la­tion will be in­fect­ed with omi­cron with­in about eight weeks.

By that time, how­ev­er, Hunter and oth­ers ex­pect the world to be past the omi­cron surge.

“There will prob­a­bly be some ups and downs along the way, but I would hope that by East­er, we will be out of this,” Hunter said.

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.

Mok­dad like­wise warned in the U.S.: “It’s go­ing to be a tough two or three weeks. We have to make hard de­ci­sions to let cer­tain es­sen­tial work­ers con­tin­ue work­ing, know­ing they could be in­fec­tious.”

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 the end of this wave, far more peo­ple will have been in­fect­ed by some vari­ant of COVID,” Mey­ers said. “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.