A pharmacist Aurora Medical Center in Grafton, Wis., deliberately removed hundreds of coronavirus vaccine doses from refrigeration and left them out overnight twice, the health system’s chief medical officer said Thursday. Mark Hoffman/Milwaukee Journal-Sentinel via AP

A pharmacist at a hospital outside Milwaukee deliberately spoiled more than 500 doses of coronavirus vaccine, hospital officials disclosed this week, as local police said they were investigating the incident alongside federal authorities.

The episode, at Aurora Medical Center in Grafton, Wis., touched off anger nationwide as limited supplies of shots are rationed for high-risk individuals. No charges were immediately announced, and the health-care system did not name the pharmacist, though officials said the person was no longer an employee.

They also did not address a possible motive, but the details became more grim with each update from Aurora Health Care. At first, the incident, in which 57 vaccine vials were discovered Saturday left outside a refrigerator, appeared to be an honest mistake. Hundreds of doses were discarded, but some were quickly administered.

On Wednesday, the health system announced its finding that the act was intentional. And on Thursday, Aurora Health leaders said the vials had been removed not once but twice, raising doubts about the effectiveness of the several dozen shots administered Saturday. Each vial has enough for 10 vaccinations but can remain at room temperature for only 12 hours and, once thawed, cannot be refrozen.

Addressing reporters Thursday, Jeff Bahr, the president of Aurora Health Care Medical Group, called the pharmacist a “bad actor.”

Police in Grafton, a village of about 12,000 that lies 20 miles north of Milwaukee, said they were investigating along with the FBI and the Food and Drug Administration. In a statement Wednesday, the local police department said it had learned of the incident from security services at Aurora Health Care’s corporate office in Milwaukee. The system serves eastern Wisconsin and northern Illinois, and includes 15 hospitals and more than 150 clinics, according to its website.

Leonard Peace, an FBI spokesman in Milwaukee, would not comment on the FBI’s involvement but said of the episode, “We’re aware of it.” The FDA also was aware, said a spokeswoman, Stephanie Caccomo, who similarly declined to address the existence of an investigation. She directed questions to the hospital.

Initiating an internal review earlier this week, hospital officials said they were initially “led to believe” the incident was caused by “inadvertent human error.” The vials of the Moderna vaccine, they thought, had simply been left out overnight Friday, and they rushed to administer doses they believed at the time were still usable. They used nearly 60 and discarded the rest, Bahr said.

As the review continued, he said, “we became increasingly suspicious of the behavior of the individual in question.”

The employee was suspended and on Wednesday “admitted to intentionally removing the vaccine from refrigeration,” Bahr said. The person, he added, also admitted to removing and returning the vaccine to refrigeration the previous night, Christmas Eve.

That acknowledgment, he said, made clear that the nearly five dozen people who received shots on Dec. 26 may not gain full protection. He said Aurora Health was working with Moderna and the FDA to “figure out a strategy” for ensuring these people are thoroughly inoculated against the virus. He also said each of those individuals had been contacted.

Bahr said there was otherwise “no evidence that the vaccinations pose any harm to them other than being less effective or ineffective.”

He said he was “not able to make any judgments on motive at this time.”

The tampering will delay inoculation for hundreds of people, Aurora Health officials said, in a state where 3,810 new cases were reported and 42 people died Thursday of covid-19, the disease caused by the novel coronavirus, according to a state dashboard.

“We are more than disappointed that this individual’s actions will result in a delay of more than 500 people receiving the vaccine,” the health system said in a statement.

Tara Smith, an epidemiologist at Kent State University and an authority on antipathy toward vaccines, said the incident will prompt medical providers to reassess who has access to the shots, even among their own employees.

“Hopefully, this is a one-off, but I’m sure places will now have to think about whether those handling the vaccines are trusted, in addition to making sure supplies are under camera surveillance,” she said.

Security has been paramount in state planning, officials say. When Wisconsin began receiving vaccine shipments in December, the health department did not disclose the eight regional hubs receiving the bulk of the materials.

Julie Willems Van Dijk, the deputy secretary of Wisconsin’s Department of Health Services, said at a Dec. 14 news conference, “This is precious vaccine. We do not want to create any security risks.” She said the state had consulted with the Department of Homeland Security on the plans.

On Thursday, Wisconsin Health Secretary-designee Andrea Palm said her department has worked with Aurora Health officials as they “investigated the situation, reviewed their processes and implemented improvements.”

“It is disappointing that any covid-19 vaccine was wasted in Wisconsin,” she added in a statement to The Washington Post.

The Wisconsin incident comes as states continue to grapple with a bumpy rollout of vaccine, which is being prioritized for health-care workers and residents and staffers at long-term-care facilities. So far, distribution has lagged far behind federal projections, as the Trump administration failed to make good its promise to deliver shots to 20 million people by the end of the year.

As of Thursday, the Centers for Disease Control and Prevention said 12.4 million doses of the vaccine had been distributed across the United States, but only 2.8 million of those had been administered. Trump administration officials have said these numbers lag behind the actual pace of vaccination, which they also vowed would accelerate starting next week.

The Moderna and Pfizer-BioNTech vaccines, the first two regimens to gain U.S. regulatory approval for emergency use, are two-shot protocols with intricate logistical requirements. Moderna’s vaccine does not require subarctic temperatures, as does the Pfizer product, but it does need to be kept cold. It can be stored at freezer temperatures for six months, the company says, and kept at regular refrigerated conditions for 30 days. It can be maintained at room temperature for only 12 hours, though, and can’t be refrozen once thawed.

Complex storage requirements are among the reasons state officials are imploring providers to administer vaccine quickly once it is received. Wisconsin Gov. Tony Evers, a Democrat, taking to Twitter last week to celebrate the start of shipments of Moderna’s vaccine, said it marked “another step forward in fighting this pandemic.”

In its original statement Monday, Aurora Health said it had successfully vaccinated about 17,000 people over the previous 12 days. Its initial review, it said, had found that the 57 vials were simply left out overnight by the employee after “temporarily being removed to access other items.” Bahr said the specific hospital where the incident occurred received no vaccine before Dec. 24.

The health system apologized, saying, “We are clearly disappointed and regret this happened.”