Frequently Asked Questions about Johnson & Johnson vaccine

On May 5, the FDA updated its authorization of the Johnson & Johnson COVID-19 vaccine, limiting its use to adults 18 and older in certain cases where other vaccines are not appropriate. This means that most people should receive either the Moderna or Pfizer vaccine, and should only get the Johnson & Johnson vaccine if other vaccines are not accessible or clinically appropriate (such as people who have had an anaphylactic reaction to a different COVID-19 vaccine) or in cases where individuals who elect to get a Johnson & Johnson vaccine would otherwise not receive a COVID-19 vaccine. 

This update was based on the latest data about the risk of developing a rare blood clotting disorder after receiving the Johnson & Johnson vaccine. While the risk of a serious adverse reaction to the Johnson & Johnson vaccine is very low and far lower than the risks for COVID-19 infection, it is higher than for the Moderna and Pfizer vaccines, which is why the CDC recommends that most people should get a Moderna or Pfizer vaccine. The identification of any possible risks, like the risks associated with the Johnson & Johnson vaccine, is a sign that the nation’s safety monitoring system for COVID-19 vaccines is working.

People who are not yet vaccinated, along with those who received the Johnson & Johnson vaccine and are now eligible for a booster shot, should get a Pfizer or Moderna vaccine. These two vaccines are widely available, but Johnson & Johnson vaccines are still on the market for cases where other vaccines are not accessible or clinically appropriate.

Updated May 6, 2022

Data show an overall rate of 3.23 cases of the blood clotting disorder per 1 million Johnson & Johnson doses administered, and the onset of symptoms for the individuals typically occurred one to two weeks after getting the vaccine. Risk varies by age and gender, but data show that the risk of developing a rare blood clotting disorder after receiving the Johnson & Johnson vaccine is highest for women age 30-49. Most people should get a Pfizer or Moderna COVID-19 vaccine, with the use of Johnson & Johnson limited to adults age 18 and older in instances where other vaccines are not accessible or clinically inappropriate.

Updated May 6, 2022

Rare adverse events associated with the Johnson & Johnson vaccine typically present within days or weeks following the shot. The risk of having an adverse reaction to the vaccine is very low, and even lower as time passes.

Data show that symptoms of a blood clotting disorder (severe headache or abdominal pain, shortness of breath, neurological symptoms, leg swelling) typically developed about nine days after vaccination, and in no cases did the onset of symptoms occur after 18 days. If you have questions or concerns, consult your doctor.

Updated December 17, 2021

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