The shortage is a result of a combination of a flu season that started early and an initiative in the city's public health department to increase its distribution of vaccinations, Curtatone said. He urged residents not to panic.
"From our perspective, everything is under control," he said.
The city used 416 vaccinations last year and received an initial supply of 420 for this season, Curtatone said. After running out, the state supplied the city with 300 more, which were exhausted on Tuesday, Curtatone said.
Last season -- and following most flu seasons -- the city ends up returning unused flu shots to the state, said Maureen Monagle, the city's public health nurse.
"It's very unusual," she said. "We've never run out of vaccinations."
A request has been submitted to the state for more shots, but the city has not heard back yet, Curtatone said. Somerville residents seeking flu shots still have options through private vendors, though they will likely have to pay a fee, Curtatone said. The city's 3-1-1 information number is prepared to help individuals find a nearby location for a shot, he said.
"There is ample supply in the community," Curtatone said.
Thursday afternoon, the city announced it received a donation of 100 flu shots for people 18 and older from the Cambridge Health Alliance. The shots will be available to Somerville residents on Thursday evenings, beginning Jan. 10, from 5 p.m. to 7 p.m. at the Somerville Health Department, at 50 Evergreen Ave, the announcement said.