The CDC and FDA will further investigate the reports of blood clots following administration of the vaccine.
US health officials are recommending a pause in the administration of the single-dose Johnson & Johnson COVID-19 vaccine following 6 reports of a rare and severe type of blood clot, according to a joint statement issued on Tuesday by the CDC and FDA.
The FDA will further investigate the cases, in which a blood clot called cerebral venous sinus thrombosis (CVST) was seen in combination with low levels of blood platelets, called thrombocytopenia. The CDC will also convene a meeting of the Advisory Committee on Immunization Practices (ACIP) on Wednesday to review the cases and assess their potential significance.
In a media briefing held on Tuesday, Peter Marks, MD, PhD, director of the FDA Center for Biologics Evaluation and Research; Janet Woodcock, MD, acting commissioner of the FDA; and Anne Schuchat, MD, principal deputy director of the CDC, discussed the details regarding the recommendation.
"We're recommending this pause while we work together to fully understand these events and also while we get information out to health care providers and [vaccine] recipients," Woodcock said in the briefing.
More than 6 millon doses of the Johnson & Johnson vaccine have been administered so far. Reports of these types of blood clots following the vaccine include 6 cases, all of which occurred in women between the ages of 18 and 48. Symptoms developed 6 to 13 days after vaccination. Of the clots seen in the United States, 1 case was fatal and 1 patient is in critical condition.
"Right now, these events seem to be extremely rare," Marks emphasized. "That said, COVID-19 vaccine safety is a top priority for the federal government." Marks added that the FDA will revise the fact sheet for health care providers and recipients to include this adverse event information. Health care providers who observe patients presenting to them with either low blood platelet counts or blood clots should establish whether or not the patient has recently been vaccinated, he said.
For individuals who have already received the Johnson & Johnson vaccine, Schuchat noted that the risk is very low for those who received the vaccine at least 1 month ago. Individuals who received the vaccine in the last couple of weeks should be aware of any symptoms.
However, Schuchat emphasized that these symptoms are different from the mild flu-like symptoms that many recipients experience in the couple of days following vaccination. Individuals who receive the Johnson & Johnson vaccine and develop severe headache, abdominal pain, leg pain, or shortness of breath within 3 weeks after vaccination should contact their health care providers.
No cases of clotting events with low platelet counts have been seen with the Moderna or Pfizer-BioNTech COVID-19 vaccines.
The ACIP will convene tomorrow to review the data on these initial cases to determine next steps.
1. Joint CDC and FDA Statement on Johnson & Johnson COVID-19. News Release. FDA, CDC; April 13, 2021. Accessed April 13, 2021. https://www.prnewswire.com/news-releases/joint-cdc-and-fda-statement-on-johnson--johnson-covid-19-vaccine-301267526.html