High vaccination rates in the Philadelphia region have contributed to a precipitous drop in the spread of the coronavirus in recent weeks, putting local officials cautiously at ease for the first time in 16 months and offering a glimpse of what post-pandemic life could look like.

The weekly average number of new COVID-19 cases dropped more quickly in Chester, Montgomery, Bucks, and Delaware Counties from April to June than it did statewide, according to an Inquirer analysis of Pennsylvania data.

Counties with the highest vaccination rates in Pennsylvania — including the four suburbs — are seeing among the sharpest declines in case rates, although some counties with lower vaccination rates have seen similar case declines. The collar counties were in the top 10 for biggest decreases, along with Allegheny, Lancaster, and others, while many counties were below the state average in case declines.

“I finally started to feel like, ‘OK, we’ve got it. We are finally where we need to be,’” said Val Arkoosh, chair of the Montgomery County Board of Commissioners. She felt as if she could “exhale” this week after a year and a half of crisis, she added. “It’s because our vaccination rates are so high. These vaccines are so effective that we’re seeing these incredibly low numbers and they’re consistently low.”

While still encouraging continued caution and vaccinations, she said she sees reasons to be optimistic. Only 11 new cases were reported Thursday in her county of more than 830,000. The physician could not recall the last time she saw a daily case count that low.

In Chester County, Commissioner Josh Maxwell noted that only three cases were reported Tuesday, the first time he’d seen single digits since the start of the pandemic.

The county leads the state with 80% of its eligible residents fully or partially vaccinated. This week its rate of positive coronavirus tests dropped to 1.9% — down from 5.7% just a month ago.

» READ MORE: Vaccinations have hit a key threshold across Pa., but still lag in Philly and some rural counties

Health Director Jeanne Franklin said the shots are a key contributor to Chester County’s decline in cases, but she cautioned that it’s still too early to declare victory.

“It will be important to see several weeks of consistently very low positivity before making any declarations about virus transmission,” she said.

Philadelphia, which has lower vaccination rates than its suburbs, was on par with the state average, with an 83% decrease in cases between the weekly averages logged April 1 and June 1. The suburban counties’ decreases approached or surpassed 90%.

The region has seen cases decline several times over the course of the pandemic. But the trend is now consistent enough to provide more confidence, officials said, along with the rising vaccination rates.

Pennsylvania has fully vaccinated 50.8% of the eligible population, while New Jersey has fully vaccinated 57.6%. For fully vaccinated eligible residents, Montgomery and Chester Counties stand at 52%, according to federal data, with Bucks at 54% and Delaware at 56%.

And some are starting to see the changes help local economies. As life creeps back toward normal — Pennsylvania reopened fully on Monday — the state’s daily new case levels haven’t been this low since September.

“We are in a great spot right now,” Bucks County Health Director David Damsker said. “I want people to take some deep breaths and realize we are coming out of this.”

‘Further along than we thought’

The counties’ vaccination rates are even higher than reported because they don’t include residents who got vaccinated in Philadelphia -- which was common, particularly in the early months of the rollout -- officials said this week after receiving numbers from the city.

In Montgomery County, for instance, 81,563 residents received at least one shot in the city, according to Arkoosh and a city spokesperson, meaning the partial vaccination rate of the county’s total population is likely around 70% instead of 61%, and its rate among eligible people 12 and older is up to 80%.

Philadelphia also administered 26,413 doses — including first shots, second shots, and one-dose Johnson & Johnson vaccines — to Chester County residents, according to spokesperson James Garrow, and 75,284 doses to Delaware County residents. (He did not provide numbers for Bucks County.)

In all, Philadelphia had fully vaccinated 184,437 nonresidents, he said, and partially vaccinated 52,148 as of Friday.

“It’s really just painting a picture that we’re further along than where we thought we were,” said Monica Taylor, vice chair of Delaware County Council.

The official county vaccination rate — 57% with at least one shot, as of Thursday — is “just the base of where we are,” she said, with as many as an additional 10% of residents vaccinated in neighboring Philadelphia.

Delaware County’s positivity rate has dropped from 9% six weeks ago to 2.5% this week. On Wednesday, it reported only 14 cases.

The high uptake of the vaccine in each county has helped the region as a whole, officials said.

“We’re really proud that Chester County residents went and got vaccines so quickly. It’s allowing our economy to open up faster. It’s given a lot of folks peace of mind,” said Maxwell, a county commissioner. “But for the vaccines, we’d still be in a very difficult situation where people would be getting sick at a very high rate.”

Closer to normal

With this progress, and a renewed focus on addressing hesitancy and access, strategies are shifting. In New Jersey, Philadelphia, and Delaware County, officials are moving away from mass vaccination sites and toward more targeted outreach and community clinics.

» READ MORE: Grassroots efforts take on vaccine barriers across the Philly region

While Philadelphia officials say it’s “impossible to say if anything in particular is driving the drop in new cases” there, they felt safe enough to lift most restrictions a week early — with an indoor mask mandate for all still in place — thanks to low case counts, few hospitalizations, and an adult vaccination rate of 66.6% with at least one shot.

“If we start to see a rise in case counts and hospitalizations locally and regionally in spite of all of that,” Garrow said, “we would begin thinking about implementing restrictions again.”

Delaware County has been holding a couple of pop-up vaccine clinics each day, including a weekly one inside Upper Darby’s 69th Street Transportation Center, Taylor said, and plans to hit every municipality at least once by the end of the summer.

» READ MORE: Can water ice, booze, and cash encourage the unvaccinated and ambivalent to get shots? Philly-area officials are finding out.

Montgomery County, meanwhile, is looking to pare down to three centrally located sites that will have shorter, evening hours and continue to give out coronavirus vaccines, as well as flu shots and other inoculations, Arkoosh said. The clinics are set to operate through at least the end of the year, she added, in order to immunize younger children when they become eligible.

Bucks County plans to keep its mass clinics open at least until 5-to-11-year-olds can be vaccinated. Chester County’s sites at Longwood Gardens and Exton Square Mall will operate at least through the end of June and middle of July, respectively, Franklin said, and can “scale up or down” in the future as needed.

This progress in combating the pandemic has also had a domino effect: Suburban main streets are starting to buzz once again, with people feeling safer returning to restaurants, shops, and other businesses.

“What we’re seeing here is that a combination of a high vaccination rate and very low case numbers is giving people confidence that we’re starting to truly get back to normal,” Arkoosh said.

Chester County surveyed residents about going to businesses and restaurants. Many said they felt safe “about getting back to normal” after having their second vaccine dose, Maxwell said.

“More than any time in quite a while, people are going out,” he said, “and seeing their friends they haven’t seen in a long time, [giving] a lot of hugs.”

Staff writer Jonathan Lai contributed to this article.