West Virginia officials accidentally gave 42 people a COVID-19 antibody treatment instead of Moderna’s vaccine.

The West Virginia National Guard said in a statement that it “learned of an error” on Wednesday that resulted in the individuals receiving Regeneron’s COVID-19 antibody treatment instead of the vaccine.

The National Guard said that the individuals have been contacted and that the West Virginia Department of Health and Human Services will follow up with those individuals as an added precaution.

The incident took place at a vaccination clinic hosted by the Boone County Health Department.

In a separate statement posted to Facebook on Thursday, the department said that “it was determined that this was an isolated incident,” adding that the individuals will be offered the vaccine.

The health department and National Guard both said they don’t believe there’s any risk of harm to the individuals.

It is unclear how the mix-up occurred. Julie Miller, an administrator for the health department, did not give additional details about the incident when reached for comment.

The West Virginia Department of Health and Human Services also didn’t provide additional details.

The Food and Drug Administration gave an emergency-use authorization for the antibody treatment in late November for treating mild to moderate COVID-19 in adults and for children at least 12 years old who have a high risk of progressing to severe disease.

The treatment — which is administered by IV administration — was one of several that President Trump received while he was staying at Walter Reed National Military Medical Center for COVID-19 in October. 

The incident is not the only one that has occurred as states race to vaccinate their populations.

Earlier this week, an employee at a Wisconsin medical center “intentionally” removed 57 vials of Moderna’s vaccine from a freezer, causing them to be discarded.