WASHINGTON — Starting this month, Americans will be able to order free COVID-19 test kits that will be mailed to their homes.

U.S. households will be able to order as many as four nasal swab tests at COVIDTests.gov when the federal program reopens. The U.S. Health and Human Services agency overseeing the program has not yet given an exact date when ordering can begin.

An agency spokesperson has said the tests will detect current virus strains and can be ordered ahead of the holiday season, when families and friends gather for celebrations.

U.S. regulators last month approved an updated COVID-19 vaccine that is designed to combat the recent virus strains and, hopefully, forthcoming winter ones, as well. The Centers for Disease Control and Prevention already has recommended this fall’s shot for everyone age 6 months and older.

While most Americans have some degree of immunity from prior infections or vaccinations or both, that protection wanes. Last fall’s shots targeted a different part of the coronavirus family tree, a strain that’s no longer circulating.