RICHMOND, Va. (AP) — Virginia is ceasing the use of all Johnson & Johnson vaccines while the federal government investigates rare reports of potentially dangerous blood clots among recipients of the vaccine.

Virginia State Vaccination Coordinator Dr. Danny Avula said in a statement Tuesday morning that the state was halting use of the vaccine until the federal investigation is complete.

“This pause is reassuring in that it demonstrates that the systems that are in place to monitor vaccine safety are working,” Avula said in the statement.

Avula added during a news conference Tuesday that the pause should not impact the state's plan to move into Phase 2 this coming Sunday. The phase means that everyone who is 16 years old and older and who lives or works in Virginia will be eligible for the vaccine.

Avula said that less than 15% of the shots that were scheduled to be given this week were from Johnson & Johnson. But the pause could result in the postponement of about 30 upcoming vaccination events this week at which about 70,000 Johnson & Johnson shots were scheduled to be administered.

In some cases, the Moderna and Pfizer vaccines will be administered instead, Avula said. But he added that some of those events will be cancelled.

Avula said the pause could last from “days to weeks.”

In a joint statement Tuesday, the federal Centers for Disease Control and Prevention and the Food and Drug Administration said they were investigating unusual clots in six women that occurred six to 13 days after vaccination. The clots occurred in veins that drain blood from the brain and occurred together with low platelets. All six cases were in women between the ages of 18 and 48.

More than 6.8 million doses of the J&J vaccine have been administered in the U.S., the vast majority with no effects or mild side effects.

Avula said that 184,000 J&J vaccine doses have been administered in Virginia.

The J&J shot requires only one shot. The Moderna and Pfizer vaccines require two shots. A total of 4.8 million vaccine doses have been given in the state, according to the Virginia Department of Health website.