As fall officially begins, the rolling average of new coronavirus cases in Pennsylvania is climbing steadily as vaccinations plateau across much of the Philadelphia region. Meanwhile, New Jersey’s average daily case count — still far higher than it was just two months ago — continues to plateau.

Hospitalizations, which experts say is a better barometer of how a largely vaccinated population is faring against the highly transmissible delta variant, have increased slightly over the last two weeks in Pennsylvania and remain steady in New Jersey.

Coronavirus-related deaths have also increased since the summer, though an average of 60 people are dying of the virus each day in Pennsylvania and New Jersey combined, a number far lower than during any prior surge. Experts say such a steep decrease in deaths shows vaccines are working.

But after an uptick in first-shot administration in August and early September, the number of first doses administered in Pennsylvania this month is far lower than the number given in August, according to an Inquirer analysis of CDC data.

The rising fall surge was anticipated by public health experts and local officials as summer ended and widespread in-person school sessions started for the first time in a year and a half.

Making matters worse, delta has sometimes been spreading among people who are vaccinated — though the likelihood of severe illness, hospitalization, and death is far higher for the unvaccinated — and increasingly cooler weather prompts gatherings to move indoors, where the risk of transmission is greater.

“We’re still in the fight,” New Jersey Gov. Phil Murphy said at a briefing Wednesday. The virus “is humbling. ... Every time you think you’ve got it figured out, it takes a turn,” most often for the worse.

If children between the ages 5 and 11 are approved to get the Pfizer vaccine in the coming weeks, and federal officials approve booster shots for select high-risk groups this week as expected, the surge could be dampened, some experts said. But the immunity from a first, second, or third shot doesn’t go into effect immediately, meaning it will take time to see the effect of either measure.

The most meaningful impact would come from have more unvaccinated people getting shots, health experts say, which is why local officials are pleading with them to start their immunizations.

» READ MORE: Unvaccinated people account for 94% of the new coronavirus cases in Pennsylvania this year, state health officials say

Murphy on Wednesday repeatedly read the words of the son of 91-year-old John Franklin, a Lakewood resident who died of the virus earlier this year: “People who refuse to get vaccinated have never seen a family member die on FaceTime. It’s awful.”

“Folks need to get vaccinated,” the governor added. “There’s just no question that that’s our best weapon.”

The rate of first dose administration across the region increased in August as people prepared for returns to school and work and some mandates went into effect with the full authorization of the Pfizer vaccine. But in Pennsylvania, September’s pace is more in line with that of July, which reported the lowest number of first shots given in the commonwealth since the start of the rollout.

More than 70% of all Pennsylvania and New Jersey residents have received at least one dose, but experts say an even higher level of protection is needed to combat delta.

In Philadelphia and its suburbs, vaccine demand has been mixed in recent weeks, according to city and county officials.

The total number of shots given in the city has been steady since mid-August, said Philadelphia spokesperson James Garrow, with about 1,800 first shots per day.

Most of the new shot recipients are Black or brown residents, Garrow said, and reside in the city’s most under-vaccinated zip codes.

Montgomery and Chester Counties have seen a slight increase in recent weeks, officials said, while Delaware County medical adviser Lisa O’Mahony said the county has “hit kind of a plateau.” Bucks County continues to report relatively low numbers at its vaccine clinics, a spokesperson said.

Chester County, meanwhile, has seen an increased demand for the one-shot Johnson & Johnson vaccine, health director Jeanne Franklin said, “so likely these individuals were on the fence or they were required to obtain the vaccine for employment purposes and the single dose was more appealing.”

More than 10,000 moderately or severely immunocompromised people in Philadelphia and its collar counties have received a third dose of a Pfizer or Moderna vaccine since it was approved for this group last month, officials said. They are preparing to expand those efforts to other high-risk groups — the more mildly immunocompromised, those 65 and older, and some frontline workers — if the FDA approves the move as expected this week.

Graphics artist Chris A. Williams contributed to this article.