Starbucks union walkout protests Covid safety at a Buffalo-area store.

With coronavirus cases surging across New York State, employees at the only company-owned Starbucks store that is unionized staged a walkout on Wednesday to protest what they say are unsafe working conditions.

Kyli Hilaire, a barista at the store, which is in Elmwood in the Buffalo area, said that it was understaffed, that workers were struggling to enforce masking rules and that many of them were anxious about their health as they watched Covid-19 case counts spike in the region.

“One of our requests was to close the store to let the outbreak of Covid run its course so we can return with a full staff rather than burning out the partners who are able to work,” Ms. Hilaire, 20, said. “They’re refusing to take the necessary precautions so our partners are not coming to work sick.”

The walkout, involving about half a dozen employees, will last the rest of the week, she added. The company said it had not determined whether the store would stay open.

Starbucks regional leaders met with union members on Tuesday night to discuss their safety concerns, which had mounted after an employee at the Elmwood store tested positive for the coronavirus. The company said all employees who had been in close contact with the infected person had been notified and given the option to quarantine themselves for five days with pay while monitoring for symptoms or awaiting Covid test results.

“We have met and exceeded all C.D.C. and expert guidelines for safety,” said Reggie Borges, a Starbucks spokesman, adding that the company was giving store and district managers leeway to adjust their operations in response to the fast-spreading Omicron variant of the virus. “All leaders are empowered to make whatever changes make sense for their neighborhood, which includes shortening store hours or moving to 100 percent takeout only, which is the case in Buffalo.”

Starbucks announced on Monday that it would reduce the number of days that vaccinated, asymptomatic workers who tested positive for the virus must isolate themselves to five days from 10, following a shift in guidance from the Centers for Disease Control and Prevention. The company also said this week that all of its U.S. workers had to be vaccinated by Feb. 9 or submit to weekly testing, in compliance with the Biden administration’s vaccine rule for large employers.

When the Starbucks workers in Elmwood voted to form their union last month, in an election recognized by the National Labor Relations Board, the result represented a challenge to the company’s long-running argument that its workers enjoy good wages and do not need a union.

“It was kind of crazy walking out of work,” Ms. Hilaire added. “It was a first for everyone.”