On Apr. 13, public health officials recommended that vaccine providers temporarily stop the distribution of the Johnson & Johnson COVID-19 vaccine after reports of rare blood clots developed post-vaccination.

On Tuesday, authorities began to investigate the connection between the vaccine and the blood clotting in the brain. Six women reported clot formations after receiving their vaccines, one person died and another is left hospitalized and in critical condition. 

So far, only women ages 18 through 48 have reported the clots, and their symptoms fully developed 13 days after the initial vaccination. However, Jante Woodcock, the acting commissioner of the Food and Drug Administration, explains that at this point there is not enough information to conclude if this particular age group is more vulnerable than others. The type of clotting scientists have found is called cerebral venous sinus thrombosis, which scientists find accompanied by low levels of blood platelets. 

In a statement, Dr. Anthony Fauci placed emphasis on the rareness of side effects from the vaccine and explains that only those who recently received their vaccine, within the last few weeks, should look out for severe headache, abdominal pain, leg pain and shortness of breath. However, the risk for those who received the vaccine more than a month ago remains very low, according to the Centers for Disease Control and FDA. 

Although the exact reasoning for the clotting in women remains unclear, many researchers at the FDA have found the possibility that the rare clotting gets triggered by an undesirable immune response in which the body produces antibodies that attack the blood platelets. Typically, when one receives a vaccine, the body’s immune system creates antibodies to fight off the virus. However, scientists believe this also explains why the platelets are depleted among the people detected with the clots. 

Despite the new rare condition, in the United States alone, more than 6.8 million people received the Johnson & Johnson vaccine since approval in February. In total, more than 190 million people nationwide have received a COVID vaccine- with most of them from Moderna and Pfizer.