A small number of people scheduled Tuesday to receive a second dose of the Moderna vaccine at Mariano's in Aurora were given the Pfizer vaccine instead.
Jeff Chaney and his son were among the small group informed they got the wrong vaccine.
Chaney said he doesn’t understand how it could happen. "I gave you my card and it said right on there, you know, first dose is Moderna, so how could you, you know, go ahead and, you know, give me the Pfizer?" Chaney said.
Chaney said he and at least a half dozen other people had just received their shots and were sitting for the waiting period when the pharmacist told them about the mistake.
Feeling out of the loop? We'll catch you up on the Chicago news you need to know. Sign up for the weekly Chicago Catch-Up newsletter here.
NBC 5 spoke to another man, who wished to remain anonymous, who also received the wrong vaccine.
"Disappointed, a little worried, nerves were kind of … we were trying to remain calm," the man said.
A spokesperson for Mariano’s confirmed the incident, sending this statement:
"The Mariano’s Pharmacy located in Aurora, IL administered a small number of Pfizer Covid-19 vaccines to people who had received the Moderna vaccine at their first appointment. No adverse events for the affected patients have been reported. All impacted patients have been contacted. We thank these patients for their understanding and have apologized for their inconvenience. Kroger Health has reported to both the CDC and the Illinois Department of Public Health, and our team is investigating the matter and will take steps to prevent a similar situation from recurring in the future."
The question the people who received the wrong vaccine are now asking: What do we do now?
"Yes, it’s a great question. We don’t know," said Dr. Michael Angarone, an associate professor of Infectious Diseases at Northwestern Medicine.
Dr. Angarone said while the two vaccines use the same mRNA technology, they are not interchangeable.
"We don't know, are they going to boost each other? And so just to be on the safe side we're saying, don't get another vaccine, don't do another series," Dr. Angarone said.
The Centers for Disease Control and Prevention offers similar guidance online: "If two doses of different mRNA COVID-19 vaccine products are administered in these situations (or inadvertently), no additional doses of either product are recommended at this time."
Those involved say they hope this is a lesson learned for vaccine administrators and offered this advice for those going to get their second dose.
"Ask them before they inject," Chaney said.
"We're all humans, so there's gonna be those slip-ups that occur. And so I think it's okay to ask and make sure I'm getting the appropriate vaccine," Dr. Angarone said.