The region is seeing a spike in demand for coronavirus testing, as infection rates climb to levels not seen since the spring and Thanksgiving approaches.

Lines at D.C.’s public testing sites have stretched for multiple blocks in recent days. Ten minutes before the site at the Judiciary Square opened Monday morning, around 300 people were already in line.

Last week, more than 25,000 people were swabbed at D.C.’s public testing sites alone, a figure that does not include private practices that conduct testing, according to Christopher Geldart, the operations chief for the city’s COVID-19 response. These city-run sites had been averaging 10-12,000 tests per week.

Geldart says that he and staff from the D.C. Department of Health regularly walk the lines at testing sites, and they’ve encountered a number of people getting precautionary tests ahead of Thanksgiving.

“There’s a good breakdown between people who are still working and may have had an exposure, … There are folks that need to get tested for work,” Geldart said Monday. “And then there are those that are planning on being with family over the holiday … All of that is adding up to what I think is our big surge in testing.”

He says, even though lines at some testing sites have been long, people are moving through at a steady pace: “We’re doing about three [tests] per minute at all of our sites.”

Geldart, who is also the director of D.C.’s Department of Public Works, notes that if residents are concerned about waiting in the outdoor lines, they can inquire about getting tested through their primary care provider.

Coronavirus cases have surged throughout the D.C. region. The District’s 7-day rolling average of daily new cases — a metric that helps account for single-day spikes — has climbed above 150 for the first time since May. The city’s transmission rate, which estimates the number of people who will be infected from one positive case, inched above 1.3 this month, a number not seen since March. And despite recommendations from local and national health officials, an untold number of locals will travel and gather for Thanksgiving dinner.

Public health experts also have warned that a negative test does not guarantee someone will not bring coronavirus to Thanksgiving dinner, in part because it’s possible to test negative one day and be positive the next.

Much like the virus, demand for testing has soared across the region. Maryland reported a daily high of coronavirus tests on Saturday — more than 51,000. Testing capacity has increased throughout the pandemic, but that number represents a significant jump. The state had been averaging nearly 31,000 daily tests between Nov. 1 and Nov. 19, according to a statement from Gov. Larry Hogan’s office.

“Over the past eight months, our state has built a COVID-19 infrastructure from scratch, including a successful long-term testing strategy,” Hogan said.

“We are seeing rising demand,” Hannah Winant, from Arlington County Emergency Management, says. It’s hard to know for sure what is causing the surge, but Winant imagines linked in part to holiday travel and increased transmission of the virus in the community.

She says Arlington is looking to boost staff at its drive-thru and walk-up test locations.

Right now, test turnaround time is between 24 and 72 hours, according to Winant. She says the county hasn’t seen delays even as demand has increased. Arlington sends its test to multiple labs — one local, one state, and one national lab — which helps prevent any one from getting overloaded, Winant says.

Arlington is also preparing to receive a batch of rapid tests from the state, part of the 200,000 antigen tests Virginia purchased through a multistate compact with the Rockefeller Foundation. The county will dedicate these tests to vulnerable populations like residents long-term care facilities.

Geldart, the D.C. official, says anytime there is a significant national surge in testing, he has some concern about lags in getting results. In D.C., the average test turnout time is now 3.5 days, crossing into a “red zone” that indicates insufficient capacity, according D.C. Health metrics. Looking specifically at public test sites, that wait time is a bit higher: inching above an average of four days, according to Geldart.

“We use our national laboratories, so as you see the amount of testing going up throughout the country, that’s a concern about the laboratories … taking longer to process tests,” he says.

The District is preparing to bring on another lab partner, in addition to its primary partner LabCorp, to process samples from public test sites.

D.C. is also expanding testing hours at several sites and, in preparation for the cold weather, opened at new location in a garage at Nationals Park on Monday. The space is not indoors, but it can be heated and has limited exposure to the elements.

Meanwhile, public health experts continue to warn that colder weather, “pandemic fatigue,” and the holidays could lead to a disastrous spike in coronavirus infections. Leaders in D.C., Maryland, and Virginia have all imposed new restrictions in recent weeks, lowering the maximum capacity for gatherings and limiting some activity at restaurants.

Dr. Amanda Castel, an epidemiologist at George Washington University, says a post-Thanksgiving spike could be worse than post-Memorial Day or July 4 because the country is starting from a higher baseline of cases.

“The overall number of cases, the spread, and the transmission could be much greater than it was over the summer in our area if people decide to get together,” she told DCist/WAMU earlier this month. She’ll be having a small Thanksgiving, with her husband and two children.

For her part, Castel says she’s forgoing the big Thanksgiving gathering this year and having dinner only with her husband and two children.

“Too often we’re hearing about people who get together with family or friends and it just becomes old familiar,” Castel says, “You let down your guard and stop practicing the things that we know can prevent transmission.”