WASHINGTON — The Biden administration is again making some free COVID-19 tests available to all American 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 to all U.S. households through covidtests.gov starting Thursday, a senior administration official said. The official spoke on the condition of anonymity to discuss the program. 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 official 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.

The official said funding for the new tests has been reallocated from other virus programs while the White House struggles to get congressional buy-in for additional COVID-19 emergency funding. The official declined to detail how much is being spent on the new tests or from which programs they were diverted.