WASHINGTON (AP) — Americans can order COVID-19 again testingsent straight to their homes without being charged.

The US government reopened the program on Thursday, allowing each household to order up to four at-home COVID nasal swab samples through the covidtests.gov website. The tests will be shipped starting next week via the United States Postal Service.

“Before you visit your family and friends this holiday season, take a rapid test and help protect them from COVID-19,” Dawn O’Connell, Health and Human Services assistant secretary for preparedness and response, said in a statement.

Why are tests being offered now?

The website has reopened after a summer COVID-19 virus surge and heading into the fall and winter respiratory virus season, with health officials insist Americans are getting an updated COVID-19 vaccine and their annual flu shot.

US regulators approved an updated COVID-19 vaccine designed to combat the recent strains of the virus and, they hope, the upcoming winter strains as well. However, the vaccination rate is decreasing. Most Americans have some immunity from previous infections or vaccinations, but fewer than a quarter of American adults received the COVID-19 shot last fall.

Using the swab, people can detect current virus strains ahead of the fall and winter respiratory virus season and the holidays. Over-the-counter COVID-19 home tests typically cost about $11, from last year. Insurers no longer have to reimburse the costs of the tests.

I have old tests that have passed their expiration date. Can I still use them?

If you already have COVID-19 tests at home, check the expiration date on the box. Many of the tests have been given an extended expiration date from the date printed on the box. You can check with the Food and Drug Administration website to see if that’s the case for any of your remaining at-home tests.

Are these tests actually free?

There is no charge for households requesting the tests, but U.S. taxpayers have already paid a significant amount for the testing program.

Since COVID-19 first emerged in 2020, the U.S. government has poured billions of dollars into developing and purchasing COVID-19 tests and vaccines. The Biden administration has distributed 1.8 billion COVID-19 tests, half of which were distributed to households by mail. It is unclear how many tests the government still has on hand.