Two of Colorado’s largest health systems are offering $500 bonuses to encourage employees to get vaccinated against COVID-19 before the end of summer, but only one plans to mandate its employees get the shot.

Employees of Centura Health and UCHealth who already have gotten vaccinated also will receive the bonus. Both systems described the payments as a way to thank those who already had the shots — and to nudge those who haven’t.

About 70% of Centura employees have gotten vaccinated across the system, but the health network wants to reach 90% protection in all hospitals and clinics, President and CEO Peter Banko said. Right now, coverage is uneven, with fewer employees vaccinated in communities where less of the general population has gotten the shot, he said.

About 1,000 people, or roughly 5% of employees, asked for information about scheduling a shot in the first week after Centura announced the bonus, Banko said. He said the hope is that incentives and encouraging conversations with people who employees trust will be enough to reach the goal without making vaccination a requirement.

“I’m trying my best to avoid a mandate,” he said.

Dan Weaver, a spokesman for UCHealth, said more than 80% of the health system’s employees are vaccinated. He said UCHealth will mandate the vaccine at some point this year, with religious and medical exemptions.

“We know that the COVID-19 vaccine provides safety not only to our employees themselves but for their coworkers and family members, and for UCHealth patients and visitors,” he said in a statement. The bonus “is both a thank-you for those UCHealth employees and contractors who have already gotten the vaccine as well as an encouragement for others to take this important step to protect others.”

Employers can legally require staff to get vaccinated; some hospitals and nursing homes have required flu shots for years. Enforcement can get messy, though. In Houston, more than 150 hospital employees who refused to get vaccinated against COVID-19 were fired or resigned. The employees filed a lawsuit, which was dismissed.

Colorado doesn’t track how many health care workers have been vaccinated against COVID-19, but health systems reported higher rates than the general population. About 63% of Colorado adults are fully vaccinated, according to the Centers for Disease Control and Prevention.

Denver Health reported about 84% of its employees are immunized, and HealthOne said about 80% are. SCL Health declined to release its vaccination rate.

Denver Health and HealthOne both reported they aren’t planning any incentives or mandates at this time, but continue to offer vaccines to those who haven’t had them. SCL spokesman Gregg Moss said they’re focusing on educational events, like town halls and webinars, to persuade those who haven’t gotten the vaccine.

To be eligible for the bonus, Centura employees need to get the first shot by July 16 and the second by Aug. 16. UCHealth employees have to complete the vaccine series by Aug. 22.

Banko estimated the bonuses will cost Centura between $6 million and $7 million, but said it’s money “best spent” to avoid deaths or long-term health problems among employees who are still vulnerable to COVID-19, as well as to protect their families.

Centura lost three employees to COVID-19, including one person who died after the vaccines became widely available, Banko said.

Any given day, 30 to 40 people can’t come to work because they have COVID-like symptoms, or are quarantining because of a high-risk exposure in the community, he said. Vaccinated people no longer need to quarantine if they are exposed to a person with the virus, but don’t have symptoms.

The current level of employees out “is not overly burdensome, but it’s 30 or 40 more than we should have,” he said.