The nurses' union, National Nurses United, said the contract addresses short-staffing and improves patient care.
More than 1,200 Cook County Health nurses planned to walk off the job for a one-day strike June 24.
They said the hospital is short-staffed.
"When you have short staffing, you're not able to take care of your patients the way you need to," Stroger Hospital Critical Care nurse Ishante Norris said. "You can't give them their medications in a timely fashion."
They lined Damen Avenue in solidarity, as many cars drove by, honking in support.
"There are other issues on the table," Stroger Critical Care nurse Falguni Dave said. "You know, obviously we as health care workers also need our health care; we need to make sure that our mental and physical state is in the right place so that we can care for the others."
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In a statement from the nurses' union they said:
"We have far too few nurses working in our hospitals and clinics and we have witnessed a reduction of services over the last 10 years that have left many patients with few - if any - options...Cook County must address our staffing crisis now."
Cook County Health, which runs Stroger and Provident hospitals, postponed some elective surgeries and rescheduled appointments. It also augmented nursing staff in priority areas like the ER in anticipation of the strike.
Cook County Health released its own statement without addressing the nurses' staffing sticking point, saying:
"Cook County Health remains dedicated to providing safe, life-saving care during this job action and beyond to meet the needs of our patients."
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Many of the nurses on strike said they felt disrespected by the negotiations, stressing they're not only speaking out for themselves.
"We want our voices heard because we are speaking up for our patients," Stroger charge nurse Bernadine Okeh said.
But the nurses' union believes the new contract will improve recruitment and retention of nurses. CCH agreed to hire 300 additional registered nurses within the next 18 months.
Cook County Health also agreed to convene an infectious disease task force in the event of an infectious disease emergency. This task force will consist of both registered nurses and managers who will meet regularly to make recommendations on how to best provide safe patient care and to create a safe work environment for nurses and other health care workers, the union said.
Wage increases are also included.
The vote was tallied Friday night and reached after nine months of negotiations.