Having a safe and effective vaccine is the top priority. All vaccines go through clinical trials to test their safety and effectiveness, including vaccines for COVID-19. The manufacturers must present data that shows the vaccine is safe and that it works before it is approved for general populations.
This data is reviewed by scientific groups at the Food and Drug Administration and the Centers for Disease Control and Prevention (CDC). After a vaccine is authorized or approved for use, many safety monitoring systems are in place to watch for possible side effects. This monitoring is critical to help ensure the benefits continue to outweigh the risks for people who receive vaccines.
The CDC and Federal Drug Administration recommended resuming use of the Janssen, or Johnson & Johnson, vaccine in the United States, effective April 23. However, women younger than 50 should be aware of the rare risk of blood clots with low platelets after vaccination and that other COVID-19 vaccines are available where this risk has not been seen. If you received a Johnson & Johnson vaccine, here is what you need to know.