Coronavirus infections at the Cook County Jail have soared in recent weeks, reaching the highest number of cases since February, data from the Sheriff’s Office shows.

As of Dec. 2, 109 detained people and 39 Sheriff’s Office employees at the jail were positive for coronavirus, according to the data.

“It’s devastating,” said Cassandra Greer-Lee, whose husband Nicholas Lee died while incarcerated at the jail in April 2020. “They’re afraid for their lives again. It’s like reliving everything all over again.”

After peaking at 200 coronavirus cases in January, confirmed cases had fallen greatly and remained relatively low as vaccines became more available. At times over the summer, there were just one or two confirmed cases at Cook County Jail.

Confirmed infections began growing quickly in November — something that’s also happened city- and statewide. Case numbers have fluctuated as new detained people enter the jail and others leave.

At the beginning of the month, there were just 14 coronavirus cases in the jail, and the infection rate was just 2.42 cases per 1,000 detainees, according to data from the Injustice Watch Jail Coronavirus Tracker.

As of Nov. 30, the infection rate was more than 18 per 1,000 detainees.

The rise in cases at the jail can be attributed to the rise of infections across Cook County, said Matt Walberg, a spokesperson for the Sheriff’s Office.

“As we have seen since the beginning of the pandemic, when COVID cases rise in the community, there is a corresponding rise within the jail within a short time,” Walberg said.

Coronavirus cases rose sharply in Chicago and the suburbs during late fall. But the infection rate in Chicago is far lower than it is in the jail, at just .18 cases per 1,000 people.

The county has taken measures to keep detained people safe, including “aggressive testing and quarantine procedures to identify any potential cases and minimize spread at the jail,” Walberg said.

About 77 percent of staff and 64 percent of people detained at the jail are vaccinated. The vaccines are “repeatedly offered and encouraged among staff and those ordered to custody,” Walberg said.

But a significant number of the infections at the jail have been breakthrough cases, Walberg said. Out of the 191 detainees who have tested positive since the start of November, 28 percent were fully vaccinated prior to getting infected, and another 5 percent were partially vaccinated, Walberg said.

Earlier on in the pandemic, there were massive outbreaks at the Cook County Jail. At one point in December 2020, at least 370 people incarcerated at the jail were infected with coronavirus.

Last year’s outbreaks intensified calls to shrink the jail population by releasing bond-eligible detainees that had been determined by a judge not to be a risk to the community.

Getting people out of the crowded jail is the only way to effectively stop the spread of coronavirus, said advocates, including Loevy & Loevy civil rights group, the MacArthur Justice Center, Civil Rights Corps, Chicago Appleseed Fund for Justice and the Chicago Community Bond Fund.

Those efforts led prosecutors, the Sheriff’s Office and public defenders to collaborate with the courts to quickly identify detained people who could be released. Over a few weeks in April 2020, the jail population shrunk by about 25 percent down to 4,000 detainees.

The county needs to replicate the mass bond reviews initiated last year and “Immediately start releasing as many people as they can,” Greer said.

But the number of people incarcerated has swelled since then beyond pre-pandemic levels, with 5,949 people incarcerated in the Cook County Jail, data from the Sheriff’s Office shows.

The increased jail population may create conditions for additional outbreaks, despite the availability of the vaccines, Greer-Lee said.

“It’s a perfect storm. That’s my biggest fear,” Greer-Lee said. “Let some people go so they can social distance. We know what we should do.”