September looks to be a barometer for how the region will fare against the highly transmissible delta variant of the coronavirus this fall, as students return to classrooms and college campuses — some for the first time in a year and a half.

“The public health community is bracing for an uptick,” said Annette C. Reboli, the dean of Cooper Medical School of Rowan University. “The next couple of weeks will tell the tale,” with “three different forces converging” — the start of in-person school, Labor Day weekend, and gatherings for religious holidays.

While the region’s rolling average of new cases per capita increased in August, and every county in Pennsylvania and New Jersey was experiencing high transmission of the virus as of Wednesday, the number of infections appears to have leveled off recently in the city, collar counties, and South Jersey, according to an Inquirer data analysis.

“There’s some evidence that we might be reaching a crest in new cases and hospitalizations,” said Philadelphia spokesperson James Garrow, noting the city’s average daily case count was the same as it was two weeks ago and percent positivity rate dropped from 7% to 4% in the same period. “Obviously, things could change, but the numbers we’re seeing this week are heartening, and we hope the trend continues.”

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After rising over the summer, virus hospitalizations have tapered off in Philadelphia and its collar counties, the data analysis shows. They are “creeping up” in New Jersey, state Health Commissioner Judith Persichilli said Wednesday, but are 50% less than they were during the April surge.

At the same time, the rate of administration of first vaccine doses continues to increase modestly, with county and city officials saying people tell them they’re getting shots now due to returns to school, concerns about delta, and mandates by employers or for participation in team sports.

“The message is for those who are unvaccinated and eligible to get vaccinated,” said Delaware County medical adviser Lisa O’Mahony. “That’s critical to creating some kind of plateau in this trajectory.”

Several public health experts say they don’t expect last week’s storm cleanup to drive cases up. While people throughout the region came together to help others after the devastation wrought by Ida, sometimes without masks, most of those interactions were isolated or outdoors, and most people who were displaced weren’t sent to packed mass shelters.

Jennifer Horney, the founding director of the University of Delaware’s epidemiology program, said neither evacuations from Ida along the Gulf Coast nor from wildfires in the West led to widespread outbreaks, so she wouldn’t expect Ida-related surges here.

“To move our [coronavirus] numbers, we’d need to see a much larger spatial and population displacement” from Ida, added Horney, who is also on the core faculty at the university’s Disaster Research Center.

Looking ahead to fall, winter

National experts have long expressed concerns about what this fall and winter could bring, particularly in light of delta. The return of in-person school, combined with dropping temperatures and more indoor gatherings, is likely to give the virus more opportunities to spread, primarily among the unvaccinated but also occasionally in the vaccinated. Last year, when vaccines weren’t yet available, case counts shot up in fall and winter.

» READ MORE: More people are getting COVID-19 tests around Philly as delta spreads and worry rises

“Projections are the winter will likely be rough. There are some wild cards in this: What happens when delta goes away or wanes? Will something that has mutated further in a worse direction replace delta?” said Reboli, a physician and dean of the Cooper Medical School of Rowan. “The clock is ticking on getting people vaccinated. We could cut down on these infections.”

Nationwide, the pace of new vaccinations has slowed since the spring. As of Wednesday, 53% of all Americans, including those under 12 not yet eligible for shots, were fully vaccinated, while 62% had gotten at least one dose, according to the New York Times. In Pennsylvania, 56% had completed immunizations, according to the Times data, and, in New Jersey, 62% had. In both states, at least 70% of their populations have had at least one shot.

Throughout the summer, delta has had particularly devastating impacts on areas with lower vaccination rates. In recent days, the governors of Idaho and West Virginia have made desperate pleas as their hospitals are flooded with patients, most not inoculated.

Nationwide, few states have more than 30% of ICU beds available, according to data from the Department of Health and Human Services. Pennsylvania was not one of them, though New Jersey was the only state in the country with more than 60% of those beds open as of Wednesday.

New prevention strategies

Along with a continued vaccination push, “layered” mitigation is key, said Horney, the Delaware professor and epidemiologist, echoing the remarks of officials in several collar counties. This means masking in public, regardless of vaccination status, as well as social distancing and hand-washing.

The recent high transmission levels — coupled with continued uncertainty about just how transmissible delta is, even among the vaccinated — prompted Montgomery County to recommend people wear masks outdoors when they can’t maintain social distance. It is the first in the region to formally do so.

» READ MORE: School year starts drama-free in some places, decidedly not in others, in wake of Pa.’s new mask mandate

While Bucks County officials say they have no plans to recommend masks outdoors, officials in Philadelphia and Chester and Delaware Counties recommend masks in crowded outdoor settings with people who are unvaccinated or whose vaccination status is unknown. And Philadelphia mandates masks at outdoor events with more than 1,000 unseated people, as well as indoors if proof of vaccination isn’t required (though that mandate did not appear to be enforced at Made in America last weekend.)

The collar counties are taking other measures, too, as the region heads into the fall — and awaits FDA approval of booster shots for adults and vaccination for children under 12. Montgomery County expects to expand the hours at its vaccination sites, a spokesperson said, and is looking into making tests more available. Delaware County, which doesn’t expect to have its health department up and running until January, is focusing on outreach about vaccines and mitigation measures, O’Mahony said, noting the county call center has noticed an uptick in calls from schools and day-care centers with positive cases.

In Philadelphia, meanwhile, testing and vaccine capacity is adequate at this time, Garrow said, with “more than 20,000 doses of vaccine being administered per week, most frequently in undervaccinated zip codes and to racial and ethnic minority groups, and the delta wave possibly cresting.”

Graphics artist Chris A. Williams contributed to this article.