Important Note about Johnson & Johnson’s Janssen (J&J/Janssen) COVID-19 Vaccine: The Centers for Disease Control and Prevention and the FDA recommended that use of the J&J/Janssen COVID-19 Vaccine resume in the United States, effective April 23, 2021. However, women younger than 50 years old should especially be aware of the rare risk of blood clots with low platelets after vaccination. There are other COVID-19 vaccines available for which this risk has not been seen. If you received a J&J/Janssen COVID-19 Vaccine, here is what you need to know.