FDA limits J&J COVID-19 vaccine due to rare blood clot risk

The U.S. Food and Drug Administration on Thursday announced it's now limiting the authorized use of the Johnson & Johnson vaccine after conducting an updated investigation into reports of rare blood clots.

Though the risk of blood clots is still extremely rare, officials said use of the Johnson & Johnson vaccine should be limited because there are other, safer options — including vaccines from Pfizer and Moderna — that do not carry the same risk.

Use of the Johnson & Johnson vaccine will now be limited to people ages 18 and older for whom other authorized or approved COVID-19 vaccines are not "accessible or clinically appropriate," and to adults who choose to receive the vaccine or else they would not get vaccinated, the FDA wrote in a press release.

The decision was made after conducting an updated analysis into reports of the rare blood clot condition called thrombosis with thrombocytopenia syndrome, or TTS, the FDA said.

"We recognize that the Janssen COVID-19 vaccine still has a role in the current pandemic response in the United States and across the global community. Our action reflects our updated analysis of the risk of TTS following administration of this vaccine and limits the use of the vaccine to certain individuals,” Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, wrote in a statement.

The FDA's action demonstrates the FDA's strong safety surveillance systems, Marks said, adding that the agency is committed to making scientific and data-driven decisions.

"We’ve been closely monitoring the Janssen COVID-19 vaccine and occurrence of TTS following its administration and have used updated information from our safety surveillance systems to revise the EUA. The agency will continue to monitor the safety of the Janssen COVID-19 Vaccine and all other vaccines, and as has been the case throughout the pandemic, will thoroughly evaluate new safety information," Marks said.

To date, nearly 17 million Americans have received the Johnson & Johnson vaccine, according to data from the Centers for Disease Control and Prevention. Scientists said that if you have already received the Johnson & Johnson vaccine, there is no need to be concerned, as the risk of blood clots happens in the days and weeks after you have received your shot.

However, if Johnson & Johnson vaccine recipients are at all concerned, health experts said people should reach out to their doctor with any questions.

The Johnson & Johnson vaccine was first authorized for emergency use by the FDA in February 2021. Just two months later, the FDA and the CDC, announced a recommended pause in the administration of the vaccine to investigate a handful of cases of TTS that had been discovered in patients across the country.

The pause was lifted just 10 days later. However, in December, after reviewing additional safety and efficacy data, the CDC’s vaccine advisory recommended that people use the mRNA vaccines from vaccine companies Pfizer and Moderna, instead of Johnson & Johnson, in most situations.

Through March 18, the FDA and CDC have identified 60 confirmed cases of TTS, including nine fatal cases, which illustrates that blood clots are a rare but real adverse event associated with the Johnson & Johnson shot.

The factors that put an individual at risk for TTS following administration of Janssen COVID-19 Vaccine remain unknown, officials said.

ABC News' Sony Salzman contributed to this report.