Motorists wait in line at a drive-up Covid-19 test site last week in Aurora, Illinois.
CNN  — 

As US coronavirus cases soar and people seek tests ahead of Thanksgiving travel, long lines are forming outside testing sites around the country, appointments are filling up, and commercial labs are warning that their capacities are being stretched.

And while the US Centers for Disease Control and Prevention on Thursday recommended not traveling for Thanksgiving and encouraged people to celebrate in person only with their own households, some health officials have offered competing messages about how – and whether – people without symptoms should get tested if they insist on gathering for the holiday.

Queues of cars have been forming outside testing sites run by states, counties, health care systems and pharmacies in numerous cities in recent days, including in the Chicago suburb of Arlington Heights.

An hour before the state-run site at the Arlington International Racecourse even opened Wednesday morning, numerous people waited in a line of vehicles snaked along several streets, video from CNN affiliate WBBM showed.

In Massachusetts, where officials are urging even asymptomatic people to get free testing in certain communities with elevated spread of the virus, people sat in cars for up to four hours Tuesday at Lawrence General Hospital’s drive-in site north of Boston, CNN affiliate WBZ reported.

“I think it’s a combination of holidays coming up, but also just the uptick in the (infection) numbers out there,” the hospital’s Dr. George Kondylis told WBZ.

In Boston, Sparsha Pun waited for a test outside Tufts Medical Center in a line that wrapped around two buildings Thursday, WBTS reported.

“I tried five different places before I got in this line, and none of them had any open spots or appointments,” Pun told WBTS.

Drivers wait in long lines for drive-through testing outside the Lawrence General Hospital in Lawrence, Massachusetts, on Tuesday.

In the town of Saugus north of Boston, cars snaked around a testing site at a mall Tuesday night, and some people waited more than two hours, WBZ reported.

“I could not believe it when it was zig-zagging five times just to get through,” Travis Morrow told WBZ about that line.

In Seattle, four city-run testing sites recently went from accommodating more than 3,000 people per day to more than 5,000, Seattle fire Capt. Brian Wallace, who also is the city’s Covid-19 testing coordinator, told CNN affiliate KIRO on Tuesday.

Wait times went up to 90 minutes even for those with appointments, he said.

Requirements at state- and county-run sites vary. Many offer free tests, though some will bill insurance for those who have it. Some try to admit only people that meet CDC guidelines – generally only symptomatic people or those who know they’ve had close contact with a Covid-19 patient – but others offer broader, surveillance testing for anyone who requests it. Some don’t require appointments.

Government-run sites can be an important alternative for those who can’t find appointments or meet qualifications at other places that offer tests, such as doctor’s offices, the Walgreens and CVS pharmacy chains and hospital and urgent care systems. They’re also an option for people who can’t find or afford at-home testing kits.

Dr. Ashish Jha, dean of the Brown University School of Public Health, said the pre-holiday scramble for tests is laying bare the nation’s limited testing capacity and lack of a national testing strategy.

“I think we should just acknowledge: We don’t have enough tests, our infrastructure is not working very well. And then get to fixing it, as opposed to denying it or downplaying it.” Jha said. “From the beginning of this pandemic the entire administration has not taken testing seriously enough and we are paying the price of that.”

People wait in a line stretching around a block outside an urgent care clinic offering Covid-19 testing in Brooklyn, New York, on Wednesday.

Labs warn of slower testing and supply challenges

The burgeoning lines, and the CDC’s recommendation against Thanksgiving travel, comes as daily new coronavirus cases and numbers of Covid-19 patients in hospitals have risen to record levels.

The average number of new daily cases across a week rose above 165,000 Thursday – the highest ever recorded, and nearly five times the average seen in mid-September, when it was at a post-summer-surge low, Johns Hopkins University data show.

These case surges could cause some commercial labs to “reach or exceed their current testing capacities in the coming days,” the American Clinical Laboratory Association’s President Julie Khani said last week.

Clinical labs already are “facing delays or cancellations on orders for critical supplies, such as pipette tips,” Khani said. Increases in wait times for test results would result, she said.

The ACLA represents lab companies such as LabCorp and Quest Diagnostics.

On Tuesday, Quest warned that average wait times for results of molecular diagnostic testing has risen slightly, to more than two days, because of surging demand.

“Assuming national trends continue, we expect Covid-19 cases and corresponding orders for testing to increase for the foreseeable future, which may cause turnaround times to grow,” Quest said.

Quest’s statement included an “appeal to personal responsibility,” calling on Americans to follow the CDC’s guidance on wearing masks and social distancing.

“We are committed to doing everything in our power” to meet demand, but “we can’t do it alone,” the company said. By following CDC guidelines, “each of us can help to reduce the spread of Covid-19, improve testing and patient care, and potentially save lives.”

In a briefing with reporters this week, Adm. Dr. Brett Giroir, the White House coronavirus testing czar, said labs were generally in good shape, and that the administration was “aggressively helping states in any way that we that we can.”

On Friday, he released a statement saying the government is closely monitoring turnaround times at ACLA labs, which he said were averaging just under two days.

“No one, and especially me and my team, is downplaying any aspect of the pandemic response, and anyone making that erroneous assertion is uninformed,” Giroir said. “The most significant issue driving the pandemic at the moment is lack of adherence to mitigation basics: mask wearing, washing hands and maintaining distance.”

Motorists wait Wednesday in long lines to take a coronavirus test in a parking lot at Dodger Stadium in Los Angeles on November 18.

Some city-run sites ask Thanksgiving travelers to stay away

For those who buck recommendations not to travel or gather with other households for Thanksgiving, health officials have offered different shades of advice on whether and how these travelers should get tested.

San Francisco officials, for instance, are begging people to not use the free testing offered at 19 city-run sites solely to make themselves confident in Thanksgiving travel.

Daily infections there are climbing, and city resources need to be focused on testing people who have symptoms or who’ve had close contact with an infected person, the city’s Covid Command Center said in an email to CNN Wednesday.

The city’s sites are testing nearly 6,000 people daily, and results on average take 24 to 48 hours, the center said.

“If people need tests for any other reason – like travel or visiting – they need to go to their private provider,” the email reads.

The city’s health director, Dr. Grant Colfax, went further this week, discouraging any Thanksgiving visits and pre-travel testing, regardless of where that testing comes from.

That’s partly because “people who test negative can still harbor the virus if they are early in their infection,” he said in a news conference Monday.

“Please do not use testing to determine whether you can travel or not,” Colfax said. “A negative test cannot be an excuse to put yourself or others at risk.”

A worker directs traffic at a Covid-19 drive-thru testing site at the Alemany Farmers' Market in San Francisco on Thursday.

The tone is different in nearby Contra Costa County. Though health officials there want people to avoid Thanksgiving gatherings, they say they suspect people will ignore those warnings.

They are encouraging people to get a drive-thru test at one of its free sites before Thanksgiving, CNN affiliate KTVU reported.

In North Carolina, the state health department urges people to not gather with anyone who isn’t part of their household. But for those that do, the department recommends quarantining for 14 days before – and getting a Covid-19 test three to four days before – the get-together.

The state is promoting more than 120 no-cost testing events being held this weekend with an eye toward helping North Carolinians “protect themselves, their loved ones, and their communities as they prepare for Thanksgiving,” Gov. Roy Cooper’s office said Wednesday.

Most of the 120 events are sponsored by the health department and will offer molecular tests, whose results times are averaging about a day and a half, department spokeswoman Kelly Haight Connor said. Events not sponsored by the department may offer antigen tests, which can yield results within an hour but are more likely to produce false negatives.

In Seattle, officials are asking people with no symptoms or known Covid-19 exposure to avoid getting testing at the city’s free sites, KIRO reported.

“Unfortunately, a lot of these tests people are doing for holiday planning may come at the expense of people that need a test because they have symptoms or known exposure,” Wallace, the testing coordinator, told KIRO.

Some colleges are encouraging students to stay through Thanksgiving, but to get tested on campus if they must leave.

This week, Connecticut Gov. Ned Lamont asked that college students returning from out of state to self-quarantine for 14 days before coming home, and get tested for Covid-19 both before leaving school and after getting home.

People wait in line for Covid-19 tests offered by the Community Organized Relief Effort, a non-profit organization in Chicago's Englewood neighborhood, on November 12.

Experts: Tests shouldn’t make people feel comfortable for Thanksgiving visits

Health experts stress a negative test result will not guarantee a person isn’t carrying the virus to a Thanksgiving gathering, because a test won’t necessarily pick up on fresh infections. An already-infected person could test negative, travel to a dinner days later and then spread the disease.

The CDC estimates 40% of infections are asymptomatic, and that more than 50% of infections are spread by people who have no symptoms.

The best advice for someone who must attend an indoor Thanksgiving dinner with a different household, experts have told CNN, is to quarantine 14 days beforehand.

“If you do that properly, you don’t need a test,” Dr. Rochelle Walensky, chief of the infectious diseases division at Massachusetts General Hospital, told CNN. “That’s probably the cleanest way to do it.”

CNN’s Curt Devine, Holly Yan, Maggie Fox, Kara Devlin, Sara Murray, Kelly Christ and Artemis Moshtaghian contributed to this report.