FILE - In this Nov. 18, 2020, file photo, people wait in a line stretching around a block, outside a CityMD urgent care clinic offering COVID-19 testing in the Park Slope neighborhood of the Brooklyn borough of New York. With coronavirus cases surging and families hoping to gather safely for Thanksgiving, long lines to get tested have reappeared across the U.S. (AP Photo/Bebeto Matthews, File)

NEW YORK (AP) — With coronavirus cases surging and families hoping to gather safely for Thanksgiving, long lines to get tested have reappeared across the U.S. — a reminder that the nation’s testing system remains unable to keep pace with the virus.

The delays are happening as the country braces for winter weather, flu season and holiday travel, all of which are expected to amplify a U.S. outbreak that has already swelled past 11.5 million cases and 250,000 deaths.

Laboratories warned that continuing shortages of key supplies are likely to create more bottlenecks and delays, especially as cases rise across the nation and people rush to get tested before reuniting with relatives.

“As those cases increase, demand increases and turnaround times may increase,” said Scott Becker, CEO of the Association of Public Health Laboratories. “So it’s like a dog chasing its tail.”

Lines spanned multiple city blocks at testing sites across New York City this week, leaving people waiting three or more hours before they could even enter health clinics. In Los Angeles, thousands lined up outside Dodger Stadium for drive-thru testing.

“This is insane,” said 39-year-old Chaunta Renaud as she entered her fourth hour waiting to enter a so-called rapid testing site in Brooklyn on Tuesday. Renaud and her husband planned to get tested before Thanksgiving, when they will drive to pick up her mother for the holiday. “We got tested before and it wasn’t anything like this,” she said.

On the one hand, the fact that testing problems are only now emerging — more than a month into the latest virus surge — is a testament to the country’s increased capacity. The U.S. is testing over 1.5 million people per day on average, more than double the rate in July, when many Americans last faced long lines.

But experts like Johns Hopkins University researcher Gigi Gronvall said the U.S. is still falling far short of what’s needed to control the virus.

Gronvall said the current testing rate “is on its way, but it’s nowhere close to what’s needed to shift the course of this epidemic.” Many experts have called for anywhere between 4 million and 15 million daily tests to suppress the virus.

Trump administration officials estimate the U.S. has enough tests this month to screen between 4 million and 5 million people a day. But that doesn’t fully reflect real-world conditions. The tests used at most testing sites rely on specialized chemicals and equipment that have been subject to chronic shortages for months.

Adm. Brett Giroir, the U.S. official overseeing testing, downplayed reports of lines and delays earlier this week. In some cases, he said, lines are caused by a lack of scheduling by testing locations, which should stagger appointments.

“I’m sure that is going to happen from time to time, but we’re aggressively helping states in any way that we can if there are those kinds of issues,” Giroir said Monday.

Marguerite Wynter, 28, stood in line for more than two hours to get a test Monday at a Chicago site. She plans on flying to see her mother in Massachusetts for Thanksgiving and staying through Christmas.