On April 13, the Centers for Disease Control and Prevention and the Food and Drug Administration requested a pause of the Johnson & Johnson vaccine out of “an abundance of caution.” There were cases of a rare type of blood clot found in six people within two weeks after they received the vaccine. There have been over 6.8 million doses of the J&J vaccine administered in the U.S.

A blood clot is a clump of blood that forms in the blood vessels that carry blood throughout the body. Blood clots are dangerous because they can block blood from flowing normally. The rare blood clots reported are called cerebral venous sinus thrombosis. They happen in the venous sinus of the brain, which are areas that drain blood into the veins that return blood from the brain to the heart.

The blood clots have been found in less than 0.000088% of people who have received the J&J vaccine. The condition is rare, but in the U.S. women in the general population experience these blood clots at a higher rate than people who have received the vaccine. In the general U.S. population, the occurrence of the blood clots for women between 1990 and 2015 was around 0.00178%.

The cases reported after J&J vaccinations were found in women between the ages of 18 and 48.

Patients who have received the J&J vaccine and who have severe headache, abdominal pain, leg pain or shortness of breath within three weeks of getting the vaccine have been asked to contact their health provider and report their illness to the Vaccine Adverse Event Reporting Reporting System.

While the use of the J&J vaccine is currently suspended, administration of the Pfizer and Moderna vaccines is continuing in Kansas and Missouri.

For those supposed to receive the J&J vaccine, the Missouri Department of Health and Senior Services said that people will be contacted if their appointment needs to be rescheduled, and their vaccine could be replaced with the Moderna or Pfizer ones instead.

For others, like older adults who can’t leave home, the J&J vaccine was the only option.