The Philadelphia Department of Public Health announced Wednesday that fewer than 5% of the city’s children ages 5 to 11 have received a first shot of COVID-19 vaccine, and warned that rising cases, particularly among children and teenagers, could signal the latest surge in the pandemic.

“This increase in cases coming at the beginning of cold weather and right before Thanksgiving could mean that we’re on the verge of another surge,” Cheryl Bettigole, the city’s health commissioner, said.

Cases are particularly rising among residents ages 10 to 19, Bettigole said, because many of them are not yet vaccinated. Contact tracing indicates these infections came through family and friends.

“Once it’s in a household, it’s likely to spread to everyone,” health department spokesperson James Garrow said. “So a majority of our cases are spread from a child to a parent or sibling, or a parent to children.”

Almost 6,400 Philadelphians ages 5 to 11 have received a first shot of COVID-19 vaccine since federal authorities approved doses for young children two weeks ago. Another 2,518 shots in the city went to children who don’t live in Philadelphia.

More than 68% of Philadelphians age 12 and older are fully vaccinated, she said. The young children who have received shots so far represent 4.8% of the city’s population of 5 to 11 year olds. That’s less than half the national vaccination rate of about 10% of all children in that age range, according to the White House.

Officials are working to encourage vaccinations to slow what Bettigole described as a “sharp uptick” in COVID-19 cases, with an average of 232 new cases per day in the past two weeks. As of Nov. 4, that average was 172 cases per day. The positivity rate of coronavirus tests has increased to 3%, up from about 2% a few weeks ago.

Still, the city’s rates now are a far cry from where they were a year ago. With no vaccine available back then and a winter surge on the horizon, the city averaged 654 cases per day and a 13.5% positivity rate.

Pennsylvania has averaged 40 cases per 100,000 residents over the past week, according to the New York Times, while New Jersey is averaging 19. Cases have increased about 30% in both states since two weeks ago. In mid-November of last year, Pennsylvania was reporting more than 6,000 cases a day; recently, it has been reporting more than 5,000 per day.

Statewide, 86,293 Pennsylvanians ages 5 to 11 have received vaccine doses.

The uptick in cases and the approach of families gathering for the holidays has health care providers concerned, particularly about unvaccinated people.

“I do think there are still enough unvaccinated people that we need to worry,” said Angie Nicholas, chief medical officer at Einstein Medical Center Montgomery and an infectious disease expert.

Hospitalizations in Montgomery County were a fraction of what they were a year ago, Nicholas said, as is the count of people on ventilators. Whether another surge could put pressure on hospitals again this winter, she said, was unclear.

“If you’re vaccinated and you get COVID, I think what we’re seeing is you’re much less likely to get seriously or critically ill,” Nicholas said. “My hope is that we have enough vaccinated people in the community that we will be able to prevent them from coming in the hospital or if they come into the hospital we can prevent them from going to the intensive care unit.”

Vaccine disparities continue

More than half of the doses administered in the city to 5 to 11 year olds went to white Philadelphians, according to city data, though whites comprise under half the population. That mirrors the demographic trends that arose when vaccines first became available. About 1,250 Black and 821 Hispanic children have been vaccinated in the past two weeks, though communities of color have been harder hit by the pandemic.

“It’s a deja vu of what we saw with adult vaccines,” said Dan Taylor, a professor of pediatrics at Drexel University.

He practices at St. Christopher’s Hospital for Children, and noted the positivity rate in the North Philadelphia neighborhood around the hospital has recently been close to 9%. The city’s vaccination rate varies widely by neighborhood as well, with some of the lowest rates in neighborhoods that are majority Black or Hispanic. Taylor has serious concerns about the consequences for children and their older relatives.

“Typically it’s not the kid who’s going to suffer from having COVID,” he said. “It’s going to be potentially the grandmother in the multigenerational housing that we have around here.”

The Philadelphia School District has already hosted vaccine clinics at schools, and has more scheduled in the coming weeks. The city anticipated the doses would be more equitably distributed as more children got shots through their pediatricians’ offices. The city also continues to host clinics in less vaccinated communities, Garrow said.

Since young children became eligible for vaccination on Nov. 2, Bettigole said, pharmacies have been a preferred source for doses. For months the city has sought to boost the number of pediatric offices providing the vaccine, health officials have said.

» READ MORE: You can now get the COVID-19 vaccine for kids in Philly. Here’s where, and other things to know.

“For this first group of people, who are really the most eager parents to get their kids vaccinated, I think people went where they can easily get appointments,” Bettigole said.

She anticipated family doctors and pediatricians will likely be the source of vaccines for parents who want more information before getting shots for their children.

“Relationships with parents and families provide an ongoing dialogue to review child developmental milestones as well as to answer parents’ questions and concerns,” said Trude Haecker, a Philadelphia pediatrician and president of the state chapter of the American Academy of Pediatrics. “These interactions can only occur in the context of the pediatric medical home.”

Pediatricians and family practices are seriously understaffed, though, Taylor said. His outpatient clinic at St. Christopher’s has had to refer patients to pharmacies because they don’t have enough staff to manage vaccinations for all the children that may want them. That, he worries, may dissuade some parents from getting shots for their children.

Approaching Thanksgiving

There’s also been an uptick of cases among residents in their 30s, likely “people who are gathering with friends, gathering with family and maybe catching it that way,” Bettigole said.

Thanksgiving, Nicholas said, poses significant risks for people who have not been vaccinated and are sick of masking and social distancing.

“We’re tired,” she said. “Nobody wants to do this any more, but that’s the only way we’re going to be able to stem the tide here.”

Residents should gather only in small groups and make sure they are protecting vulnerable family members, she said.

» READ MORE: Philadelphia-area pediatricians are ready to give young kids their COVID-19 shots, but staff shortages loom

The surge also corresponds with a decrease in mask use in the city, Bettigole said. Although an indoor mask mandate remains in place, she said more people have let their guard down and stopped wearing them.

”I know everyone wants to talk about when we’re going to get rid of masks,” she said, “but this is not the time.”

Staff writers Justine McDaniel and Erin McCarthy contributed to this report.