On May 5, 2022, the U.S. Food and Drug Administration (FDA) issued limitations on Janssen COVID-19 Vaccine to be used only for adults who are unable to access or who would not otherwise receive an authorized or approved COVID-19 vaccine including Pfizer-BioNTech COVID-19 Vaccine (COMIRNATY) and Moderna COVID-19 Vaccine (Spikevax). For individuals who elect to receive the Janssen COVID-19 Vaccine, it is authorized as a single primary vaccination dose and as a single booster dose at least two months after completing primary vaccination with Janssen COVID-19 Vaccine or a different COVID-19 vaccine. The FDA authorized emergency use of Janssen COVID-19 Vaccine for adult patients on February 27, 2021. The limitations were recently imposed after evaluating the risk of thrombosis with thrombocytopenia syndrome (TTS) associated with administration of the Janssen COVID-19 Vaccine. TTS is a rare but potentially life-threatening syndrome resulting in blood clots and low levels of blood platelets that have been reported in patients within two weeks following administration of the Janssen COVID-19 Vaccine. Symptoms of thrombosis, or blood clots, may include severe headaches, vomiting, visual impairment, or pain and swelling in limbs. Symptoms of thrombocytopenia, or low platelets, may include bruising and round purple spots on the skin due to bleeding.