42 people mistakenly given antibody treatment instead of COVID-19 vaccine

Over three dozen people were mistakenly given the Regeneron monoclonal antibody treatment instead of the Moderna vaccine, the West Virginia National Guard announced on Thursday

Forty-two people received the antibody product, intramuscularly, at a vaccination clinic hosted by staff at the Boone County Health Department. The treatment, which was given Food and Drug Administration emergency use authorization in November, is normally given as an intravenous infusion.

"It has been determined that this was an isolated incident," Julie Miller, an administrator for the Boone County Health Department, told ABC News.

Medical experts with the Joint Interagency Task Force do not believe there is any risk of harm to these 42 individuals, and all individuals who received the monoclonal antibody have been contacted or are in the process of being contacted, according to the West Virginia National Guard.

Regeneron is a drug cocktail consisting of antibodies designed to fight COVID-19. The drug was administered to President Donald Trump when he became ill with the virus.

"The moment that we were notified of what happened, we acted right away to correct it, and we immediately reviewed and strengthened our protocols to enhance our distribution process to prevent this from happening again," Maj. Gen. James Hoyer, adjutant general of the West Virginia National Guard, said in a press release.

Because there is currently no data on the safety and efficacy of mRNA COVID-19 vaccines in persons who received monoclonal antibodies as part of COVID-19 treatment, the Centers for Disease Control and Prevention recommends that "vaccination should be deferred for at least 90 days, as a precautionary measure until additional information becomes available, to avoid interference of the antibody treatment with vaccine-induced immune responses."

However, despite the CDC's recommendation, the West Virginia National Guard told ABC News that "there are no concerns that this will set individuals back 90 days," and that "all 42 individuals are being offered the vaccine today."

Miller said the Boone Health Department will continue to work closely with the state National Guard and the West Virginia Department of Health and Human Resources to review all internal policies and procedures.

"While this injection is not harmful, it was substituted for the vaccine. But this occurrence provides our leadership team an important opportunity to review and improve the safety and process of vaccination for each West Virginian," Dr. Clay Marsh, the state's COVID-19 czar, said.

ABC News' Sony Salzman and Sasha Pezenik contributed to this report.