COVID-19 cases and deaths are declining in Philadelphia and its surrounding suburbs, prompting health officials in the region to express cautious optimism that the worst of the omicron surge may be over.

In Philadelphia and its four neighboring Pennsylvania counties, hospitalizations are declining too, and city hospitals are beginning to feel relief from the press of COVID-19 patients that has swamped them in recent weeks.

“Will that continue?” said Philadelphia Health Commissioner Cheryl Bettigole in a news conference Wednesday. “It depends on how people behave, among other things.”

Though case counts remain high, the number of new daily infections in Philadelphia, its collar counties, and South Jersey all appear to have peaked between Jan. 9 and 12, an Inquirer analysis showed. Since then, the average daily cases over the last week have dropped by more than a third in South Jersey, by 40% in Philadelphia, and by almost a quarter in Delaware, Chester, Bucks, and Montgomery Counties.

The declining case trends in Philadelphia mirror those in other Northeastern cities. Health officials tempered optimism, though, with a reminder that the omicron surge may be waning but isn’t over.

“I need to just point out and remind everyone we are still seeing thousands of cases a day on average, which is more than we have seen a day during this pandemic,” said Val Arkoosh, the chair of Montgomery County’s Board of Commissioners and a physician. “There will be ongoing impacts.”

The surge brought record-high case numbers to Pennsylvania, New Jersey, and the United States as a whole, infecting tens of thousands more people in this region. Some city-area hospitals were strained, though most weren’t as burdened as hospitals in certain other parts of Pennsylvania. If current trends continue, the region appears poised to be spared the death rate it reached last winter, and shouldn’t approach the mass fatalities of spring 2020.

Both Bettigole and New Jersey Gov. Phil Murphy also noted case counts remain far higher than at most other points in the pandemic. In Philadelphia, the seven-day average of new daily cases as of Tuesday was 1,979 — lower compared with more than 3,500 daily a week ago, but the highest peak prior to omicron was about 1,000 cases a day, Bettigole said. And while regionwide hospitalizations are down, Philadelphia’s 1,432 COVID-19-positive hospital patients this week are more than a week ago.

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The positivity rate in Philadelphia is currently 21%, and health officials say a number that high indicates the virus is transmitting beyond testing’s capacity to capture the full extent of its spread.

“We are still in the thick of it,” Bettigole said. “Things are better, but we’re a long way from safe right now.”

New Jersey reported 8,465 new cases Wednesday, fewer than daily totals earlier this month, Murphy said, but also higher than tallies through most of 2021.

“We cannot look at a falling number and fall into complacency,” Murphy said. “Omicron inundated us once. We do not wish to see that happen again, and it can if we let our guards down.”

U.S. omicron cases first began rising in the Northeast, so while the wave may have crested here and in some West Coast cities, they are still rising elsewhere.

“The challenge is that the entire country is not moving at the same pace,” Vivek Murthy, the U.S. surgeon general, said Sunday. “The next few weeks will be tough.”

Nationally, health officials are predicting the omicron surge could result in 50,000 to 300,000 American deaths by March, the Associated Press reported. Evidence continues to mount that the omicron variant is less severe than other strains of COVID-19 but has a higher transmissibility. A smaller percentage of people infected are getting seriously sick, but so many people are being infected, the numbers of seriously ill are still huge. And the case counts were so high earlier this month, even a big decrease means the number of infected people is still high in comparison with other points in the pandemic.

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“It was starting from a really high place,” said Jennifer Horney, founding director of the University of Delaware’s epidemiology program. “It’s still a really high place.”

What the latest numbers mean for the long-term path of the pandemic remains unclear. If omicron’s victims gain immunity against other forms of COVID-19 from their infections, there is the possibility the latest variant could be a step toward COVID-19 becoming endemic, a permanent addition to the bugs and viruses we all deal with, but one with only sporadic outbreaks.

“It’s not just going to fade away,” Horney said.

It is too soon to say, though, if omicron will be the final surge. The variant emerged because the low global vaccination rate allowed the virus to keep spreading and mutating, and another new variant could emerge in the future, said public health officials, stressing the importance of getting vaccinated and boosted now.

“The answer is we do not know that, and I think we have to be openly honest about that,” Anthony Fauci, the president’s chief medical adviser, said Monday at the World Economic Forum’s Davos Agenda. “I would hope that that’s the case, but that would only be the case if we don’t get another variant that eludes the immune response to the prior variant.”

Keeping case, hospitalization, and death numbers trending downward depends on people continuing to exercise restraint, Bettigole said. About 78% of Philadelphians 18 and older have had two doses of Pfizer or Moderna vaccine, or a dose of the Johnson & Johnson vaccine, but only 261,540 people have received booster shots, just over a quarter of the city’s vaccinated population.

Bettigole attributed that low number to people’s reluctance to again experience the possible mild side effects of vaccination, but she said booster shots were critical.

Murphy on Wednesday announced that workers in health-care settings and high-risk congregate facilities would be required to get booster shots.

“With omicron, we really need the boosters to be fully protected,” Bettigole said.

Bettigole has noted cases likely surged because family and friends gathered for Christmas but are declining now in part because people chose to restrict their socializing for New Year’s Eve.

“It’s not time to throw caution to the wind and live it up,” said Chrysan Cronin, professor of public health and epidemiologist at Muhlenberg College. “What we’re doing seems to be working, so let’s keep doing it.”