WASHINGTON — The Biden administration is again making some free COVID-19 tests available to all U.S. households as it unveils its contingency plans for potential coronavirus surges this winter.

After a three-month hiatus, the administration is making four rapid virus tests available per household through covidtests.gov starting Thursday. COVID-19 cases have shown a marked increase after the Thanksgiving holiday, and further increases are projected from indoor gathering and travel around Christmas and New Year’s.

The administration is putting personnel and equipment on standby should they be needed to help overwhelmed hospitals and nursing homes, as was necessary in earlier waves of the virus. So far there have been no requests for assistance, but surge teams, ventilators and personal protective equipment are ready, the White House said.

The Biden administration is also urging states and local governments to do more to encourage people to get the updated bivalent COVID-19 vaccines, which scientists say are more effective at protecting against serious illness and death from the currently circulating variants. The administration is reiterating best practices to nursing homes and long-term care facilities for virus prevention and treatment and is urging administrators as well as governments to encourage vulnerable populations to get the new shots.

The planning comes as the administration has struggled to persuade most Americans to get the updated boosters as cases and deaths have declined from pandemic highs and most people have embraced a return to most of their pre-pandemic activities.

A White House official said the new tests would come from the national stockpile, which still has reserves after the administration shut off the at-home testing program in September. New tests would be procured to replace tests distributed over the coming weeks under existing funding authorities. The Biden administration is still asking Congress for billions of dollars in additional funding for the virus response.