WASHINGTON — Federal health officials today pressed nursing home workers to get their booster shots amid a spike in COVID-19 cases among staffers and a concerning lag in booster vaccination for residents and staff.

The omicron variant “is lightning fast, and we cannot afford another COVID-19 surge in nursing homes,” Health and Human Services Secretary Xavier Becerra said in a livestreamed appeal to the industry. “You know that. I know that. Higher numbers of COVID cases would likely once again have a devastating impact on our loved ones.”

Nursing homes are a testing ground for President Joe Biden’s assertion that the United States is much better prepared to handle a surging virus than it was last winter. Although residents are a tiny proportion of the population, they represent a disproportionate share of Americans who have died in the coronavirus pandemic. Earlier this year the advent of vaccines brought the virus under control in nursing homes and allowed them to reopen to visitors. But that return to normalcy could be in jeopardy as omicron pushes COVID-19 cases to highs.

Cases among nursing home staffers jumped to 10,353 for the week ending Dec. 27, a rise of nearly 80% from the previous week, according to data from the Centers for Disease Control and Prevention. Staff deaths increased to 58, tripling from the previous week. Among residents, who are more heavily vaccinated, cases went up slightly and the data showed no increase in deaths.

With medical experts advising that a booster shot is critical to defend against omicron, Becerra said only 57% of nursing home residents and 25% of staff and have gotten boosters. That’s clearly behind a booster rate of nearly 66% among people age 65 or older and about 45% for the adult population, according to statistics from the White House.

“We’ve got to change that,” Becerra said.

The administration is urging some 1,400 federally funded community health centers across the land to partner with local nursing homes in a renewed vaccination campaign.

Nursing home workers were supposed to be fully vaccinated by Jan. 4 under an earlier order issued by the Centers for Medicare and Medicaid Services, which required staff at health care facilities that receive government money to get their shots. That directive got ensnared in litigation and the Supreme Court has set a special session next week to hear arguments on it, along with the much broader Biden administration vaccine mandate for workers at larger companies of all kinds. Together the orders would affect about 100 million employees.

“Once again nursing homes are really the ground zero,” said Harvard health policy professor David Grabowski, who has tracked the impact of the pandemic on residents and staff. “How well we do in combating this virus can often be discerned by just looking at the nursing homes.”

Grabowski said the Biden administration is right to raise the alarm now. “We see this time and time again: When staff (infection) rates go up, resident rates go up,” he explained. Staffers unwittingly bring in the virus from surrounding communities, a common trigger for nursing home outbreaks.

Vaccines enabled nursing homes to weather the delta variant surge earlier this year, and timely booster shots should go a long way toward blocking omicron. “The more vaccines and boosters we have, the more lives we are going to save over the course of the winter,” Grabowski said.

But some states are already seeing trouble.

COVID-19 outbreaks in Mississippi nursing homes have almost doubled in the past week, and officials say that indicates the state is probably heading into another major surge of virus cases and hospitalizations.

There were 63 outbreaks in Mississippi nursing homes Monday, about twice the number reported last week, state epidemiologist Dr. Paul Byers wrote in a midweek memo to Mississippi hospitals and health care providers.

Along with other data, that points to “very rapid growth of COVID-19 infection and transmission…we have now entered our 5th wave of COVID-19 in the state,” Byers wrote.

One of the major nursing home industry groups is backing the administration’s push on boosters.

The American Health Care Association said in a statement it’s asking members to “double down on their efforts to get as many residents and staff fully vaccinated and boosted as soon as possible.”