More teenagers in St. Louis County are testing positive for the coronavirus than any other age group just as schools are back in session with fall activities and sports.

County Executive Sam Page drew attention to the alarming trend in his press briefing Wednesday.

Since June, the highest rate of new infections has been seen in young people in their 20s, presumably due to a ramp up in summer activities and time spent at bars, which were later shut down late at night in response to those rising numbers.

But now the 15-19 age range is seeing more cases than the 20-29 age range, a trend especially noticeable for the last few weeks and reinforced by data collected by contact tracers, Page said.

“This jump is not unexpected, but it’s worrisome,” Page said.

The county is currently seeing almost 20 new cases a day in that age group, a “very dramatic increase beginning in July until end of August” that Page said is “not based on any single event or any single gathering, rather it’s just our teenagers who are out and about. Teens do what teens do — they hang out with friends, they go to events, sometimes they go to school-related activities- normal activities, but during an extraordinary time.”

Although teenagers typically do not see severe levels of illness from COVID-19, studies have shown that they can spread it as easily as adults do, and they might live or come into contact with higher-risk older adults.

“We know that they can also take it home and spread it to others who have a high risk of becoming seriously ill, and this is why we emphasize again and again the importance of social distancing — and this is more challenging as people gather together in groups,” Page said.

As the summer wave of cases has risen in the St. Louis region, the percentage of COVID-19 patients in intensive care and on ventilators has gone down to where it was during the first spike in April and May. That is because of the rising cases in young people, who are less likely to have severe cases of the respiratory illness, said Dr. Alex Garza, SSM Health CEO and commander of the St. Louis Metropolitan Pandemic Task Force, in a briefing Monday.

“It’s a different patient population — it’s younger, not as much chronic diseases, and we’ve done better at taking care of these patients to prevent them going into the intensive care unit,” Garza said.

In a setback, the St. Louis region saw its largest one-day spike in hospital admissions in data reported Wednesday that lags two days. The four major hospital systems reported 71 new hospital admissions, up from 43 the day before. Before that, the seven-day moving average of hospitalizations had plateaued around the 40-a-day level for the last month, not improving but not getting worse, Garza said.

But it’s unclear why the cases are rising among teenagers, Garza said, other than they appear to be resuming activities they commonly did pre-COVID such as gathering in groups, not socially distancing and not wearing masks. The trend is seen across the entire region, not just St. Louis County.

“You can think about the things that kids commonly do which is coming together to practice sports or for social gatherings or for other things,” Garza said. “That is most likely what’s driving the spread. … There’s nothing special about the age group that makes them susceptible to COVID. The logical reason is gathering in large groups and not social distancing and not wearing masks.”

In restrictions put back into place in late July due to the summer rise in cases, Page banned all gatherings above 50 people in St. Louis County. But other areas in the region don’t have any such bans.

Other areas in the region are starting school in person, while most St. Louis County school districts are starting the year all-virtual. In late July, Page recommended that all St. Louis County school districts start the school year all-virtual.

Every South County school district is starting all-virtual except Lindbergh Schools, which is starting with K-3 classes in person with rotating first days for 50 percent of students this Thursday and Friday.

South County itself has been a hotspot for new coronavirus cases in the last few weeks and that trend continued over the last week. Garza singled out the Affton and Green Park 63123 ZIP code as one of the ZIP codes with the most new cases, along with Hillsboro and Festus in Jefferson County. Two weeks ago, Garza singled out Oakville’s 63129 ZIP code, Concord’s 63128 ZIP code, Sappington and Arnold as COVID hotspots. Concord and Oakville continued to rise in cases at nearly the same pace in the latest data released.

Mehlville Fire Protection District Chief Brian Hendricks told The Call that he was glad Page recommended that schools go virtual to keep the number of cases down.

“I’m worried about when schools open up, what that’s going to be,” Hendricks said. “I can only say how happy I am about the decision that the county executive has made. It’s hard, this is a tough time.”