LITTLE ROCK, Ark. (AP) — Arkansas is joining other states in temporarily halting use of the Johnson & Johnson coronavirus vaccine while a federal review is underway.

The Arkansas Department of Health says vaccination clinics with the Johnson & Johnson vaccine are canceled, but ones offering the Pfizer or Moderna vaccines will continue as planned.

The Centers for Disease Control and Prevention and the Food and Drug Administration said Tuesday they were investigating unusual blood clots that occurred 6 to 13 days after vaccination. More than 6.8 million doses of the J&J vaccine have been administered in the U.S., the vast majority with no or mild side effects.

Over 31% of the people in Arkansas have gotten at least one dose of a coronavirus shot, while 19% are fully vaccinated, according to the CDC.