Utah’s hepatitis A outbreak has expanded to more than 160 cases, with at least 21 confirmed in the past month, but officials say the growth is not tied to possible restaurant exposures in Salt Lake and Utah counties.

The majority of cases, 108, have been reported in Salt Lake County, with another 38 in Utah County, according to Utah Department of Health data updated this week. The outbreak began last summer and is one of three around the country.

The outbreak has occurred primarily in the state’s homeless population. But in early January, health officials alerted the general public about infected people who had worked at Spanish Fork Olive Garden and Sonic Drive-In restaurants and at a West Jordan 7-Eleven, saying several thousand customers may have be exposed. They set up hotlines and urged some patrons to get vaccinated.

The effort appears to have worked. Neither county has confirmed additional cases stemming from the infected workers. The disease — which inflames the liver and is occasionally deadly — usually spreads when traces of infected feces reach the mouth through contaminated food, water or unclean hands.

Nicholas Rupp, a spokesman for the Salt Lake County Health Department, said there’s a chance that there could be cases from the restaurants because the disease has an incubation period of up to seven weeks.

To prevent further scares, Salt Lake health officials on Thursday announced that if any restaurant worker has been in contact with someone infected with the disease, all other workers at that location must be vaccinated. The temporary amendment to the county’s health regulations is scheduled to last 120 days and could be extended.

Rupp said the health department has vaccinated workers at several restaurants it believed were at risk, but its wanted to formalize the requirement for any restaurants where workers could have been exposed.

The number of new cases in Salt Lake County peaked in late December, but January has continued to see a handful of new infections each week. “We’re kind of status quo in terms of the number of cases coming in,” Rupp said.