WASHINGTON - Federal health officials on Thursday 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 can’t 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 … and we know we just have to work doubly hard to keep them safe.”

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 new highs for the nation.

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 adults of all ages, according to statistics from the White House.

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