Washington (AFP) - Days out from Christmas, Americans are facing long lines to get tested for the coronavirus amid a new surge driven by the Omicron variant and a dire shortage of options for this vital screening measure.

Scenes reminiscent of the first wave from the spring of 2020 played out across Boston, New York and California -- despite the country now facing its fifth wave.

In the heart of the capital Washington, a free testing site a few blocks from the White House hadn't seen such crowds in a long time. 

A queue snaked all around the square and eventually led up to a group of small white tents.

Just two weeks ago, the site was doing 150 tests every morning. By Monday the figure was up to 600, and on Tuesday, a manager estimated there would be 800 tests. The center has had to recruit more staff.

Michael Lehman, a 56-year-old management consultant, said he waited just over 40 minutes, which he considers "kind of quick." 

He'd received a notification about an exposure, and doesn't want to pass the virus on to his children, who are due to visit him from California for the holidays.

Though the result should be ready by Christmas Eve, it definitely won't be back the same day -- a fact that irks some people.

"I'm going home today," said Leah Kovach, a 22-year-old from South Carolina who began experiencing symptoms last night. 

"I tried to get an appointment, but they're all blocked up. So here I am," said Kovach, who works for AmeriCorps and had to use up a personal day to get tested.

With her single dose of the Johnson & Johnson Covid vaccine, she admits to being a "little nervous" after hearing that the shot doesn't stand up well to Omicron, now the dominant strain in the country.

Good luck finding a home test

Getting a rapid test in Washington currently feels like mission impossible: pharmacies have few appointments left, while at home self-test kits are scarce treasures.

Tips about stores that have them are passed along by word-of-mouth, much like toilet paper in the early part of the pandemic.

"We looked online for at home test kits and they're sold out all over the city," said 75-year-old Ellen Harrison, wearing a hat to protect her from the cold 37 degrees Fahrenheit (3 degrees Celsius) temperature.

She went to a pharmacy that was supposed to have some, only to leave empty-handed.

US President Joe Biden on Tuesday announced the government's purchase of 500 million rapid tests. 

They will be distributed for free to Americans who want them...from January.