President Biden said that he would set up new federal coronavirus testing sites nationwide to mitigate the Omicron variant of the coronavirus. The first of those sites will open in New York City before Christmas.

The move comes after New York City officials announced that they would open an additional 23 coronavirus testing sites by the end of the week to try to meet a soaring demand as people race to learn their status before holiday travel and indoor gatherings.

“Testing helps us on so many levels,” Mayor Bill de Blasio told reporters on Monday. “It helps to make sure that each person knows where they stand. On the very personal level, when you get tested, you know what’s going on, you know what to do.”

By the end of this week, New Yorkers will have 112 city-run sites, which are spread out among all five boroughs and have been opened in various settings, including health care facilities, schools, libraries and community centers.

The city estimates that more than 130,000 people are being tested at the city’s sites every day, which is double the number three weeks ago. New Yorkers also have access to hundreds of private testing sites across the city.

Here’s how to be tested for Covid-19 in New York.

Who can get tested?

Essentially everyone, including people who do not live in New York, regardless of whether they have Covid-19 symptoms. But certain sites have minimum age requirements, which are listed on the city’s coronavirus portal.

Where can I go?

You can find a list of city-operated and privately run testing locations on the city’s portal. You can also text “COVID TEST” to 855-48.

Each site is supposed to specify what tests are available and when results can be expected. The portal also lists if an appointment is needed to visit a particular location and whether there are other requirements such as a screening to see if you were recently exposed to the virus or a doctor’s order for a test.

The hours for each site are also listed. The N.Y.C. Health + Hospitals/Gotham Health locations and saliva self-testing sites will stop testing at 2 p.m. on Friday. All mobile testing sites will be closed Christmas Day.

While city-run sites are without cost, some private testers charge a fee. Poor weather may also force some locations to close. City officials encourage people to call a testing site before going.

How can I tell if a private testing site is reputable?

The New York State Health Department is in charge of regulating all private testing sites, including sites in New York City.

But certain testing sites have recently come under increased scrutiny. The New York attorney general Letitia James on Monday issued a warning to LabQ Diagnostics, a Brooklyn-based laboratory with testing sites across the city, over false advertising. The company’s website advertises test results within 48 hours, but some people have reported waiting more than 96 hours.

How long will I have to wait?

Many New Yorkers have seen lines at testing sites snake around blocks, and the wait can sometimes exceed two hours.

The wait time at the N.Y.C. Health + Hospitals locations can be tracked using this dashboard. For example, the site lists test locations with no reported wait time as well as sites that have wait times of more than two hours. Workers aim to update the expected wait times every two hours.

How do I find an at-home test?

New Yorkers with certain underlying health conditions or who are over 65 can schedule an in-home appointment by calling 929-298-9400, seven days a week, between 9 a.m. and 7 p.m.

At-home tests can also be ordered online, through one of five different vendors: Hims & Hers, Pixel by LabCorp, QuestDirect by QuestDiagnostics, Vault Health or Zeel. The cost of the tests largely depends on what insurance carriers cover. In some cases, a screening to check if you were recently exposed to the virus must be completed before an order can be placed.

Testing kits have become hard to find in pharmacies and other stores, and some retailers are charging higher prices. The attorney general’s office on Tuesday condemned price gouging and asked people to report it.

What should I do if I test positive?

You should quarantine for 10 days and contact your medical provider or call the city at 1-212-COVID-19. The New York City Test & Trace Corps offers help to those who test positive, such as a hotel room in which to quarantine, food or medical support like medicine and mental health care.

Those infected should try to determine when they might have been exposed and reach out to people they interacted with and had close contact with during that time period. The state health department recommends reaching out to people you were in close contact with starting two days before your symptoms appeared — or if you are asymptomatic, two days before taking your test.

They may hear from a contact tracer who will help notify people who might have been in contact with them and connect people with resources.