Close study of the Johnson & Johnson vaccine suggests that the chance of severe adverse reactions such as blood clots with low platelets is very small – but present. As of March 18, 2022, more than 18.5 million doses of the Johnson & Johnson vaccine have been given in the US. Of those 18+ million doses, the CDC and FDA identified 60 confirmed cases, including 9 which were fatal, of people who had the Johnson & Johnson vaccine and later developed thrombosis with thrombocytopenia syndrome (TTS).

While the risk of TTS (a rare syndrome that could lead to blood clots) is very low, the FDA has chosen to restrict the use of the Johnson & Johnson vaccine to adults who otherwise would not receive a COVID vaccination (since the risks of harm from COVID are much, much greater).

On May 5, 2022, the FDA limited the authorized use of the Johnson & Johnson COVID-19 vaccine to:

  • Adults (18 or older) who cannot receive the Pfizer or Moderna vaccines (either because of availability or health reasons)
  • Adults (18 or older) who choose the Johnson & Johnson vaccine or not receiving any vaccine at all.

If you are considering receiving the Johnson & Johnson vaccine, please consult with your doctor to see if it’s a good choice for you.

Also, as of January 27, 2022, more than 517 million doses of the Moderna have been given in the US. Of those 517+ million doses, there have been 3 confirmed cases of people developing TTS after receiving the Moderna vaccine. However, it should be noted, it has not been determined if the timing was coincidental or if there was a connection between the Moderna vaccine and the TTS onset.

There have been no reports of blood clots with the Pfizer vaccine.

Please note, the number of doses and the number of health events change daily. For more up-to-date data, please visit the CDC’s Adverse Events after COVID-19 Vaccination report linked below. Their report is updated regularly.


Updated 05/06/2022