Rare cases of blood clots linked with Johnson & Johnson's COVID-19 vaccine look similar to reports of clotting in people who had received a vaccine developed by AstraZeneca, according to a top federal health official.
The rare blood clots linked to the AstraZeneca COVID-19 vaccine could help U.S. health officials as they investigate six reported cases of blood clots, including one death, associated with the J&J vaccine, said Peter Marks, M.D., Ph.D., director of the Center for Biologics Evaluation and Research at the Food and Drug Administration (FDA).
The FDA recommended Tuesday that vaccination sites suspend the use of Johnson & Johnson’s COVID-19 vaccine while the rare cases of blood clots are investigated. Since the vaccine’s late February emergency use authorization in the U.S., nearly 7 million people have received the shot. Six recipients of the vaccine—all women between 18 and 48—were diagnosed with rare blood clots afterward, with symptoms occurring six to 13 days after vaccination, the FDA says. One died and one is in critical condition.
In these cases, a type of blood clot called cerebral venous sinus thrombosis was seen in combination with low levels of blood platelets (thrombocytopenia). The rare blood clots need to be treated differently than typical clots, officials said. In fact, standard treatments, such as the administration of an anticoagulant drug called heparin, can worsen a patient's condition.
Doctors should avoid using heparin, because in these clots it "can cause tremendous harm, or the outcome can be fatal," Marks said during a webinar hosted by the American Medical Association Tuesday.
The Centers for Disease Control and Prevention's (CDC's) outside vaccine advisory committee has planned an emergency meeting Wednesday to review the cases. The FDA will then review that analysis "in the totality of the evidence that the FDA has," Marks said.
"That advisory committee may make recommendations about what can be done so people know what to report, for example, if you develop certain symptoms you should seek medical attention. Or, they may recommend that certain populations avoid this vaccine. We don’t know whether they will go there," Marks said.
How long the FDA's recommended "pause" on the use of the J&J vaccine will last depends on what the CDC advisory committee and the FDA learns in the next few days, he said.
"We are committed to an expeditious review of the available information and aggressive outreach to clinicians so they know how to diagnose, treat and report," Anne Schuchat, M.D., principal deputy director of the CDC, said during a call with reporters Tuesday.
"One of the things the Advisory Committee on Immunization Practices' deliberation will do is review the data on the cases, and the context of risk-benefit and possible subsets of populations that may be in a different category in the days ahead," she said.
There have been 180 million doses of the Pfizer and Moderna COVID-19 vaccines administered in the U.S. and no reports of cerebral venous sinus thrombosis in combination with low levels of blood platelets, Marks said.
The six confirmed cases involve women between 18 and 48 but, to date, there is no clear association between the rare blood clot cases and the use of oral contraceptives, Marks said.
While the rare blood clot cases only involve six cases, the pause was necessary to ensure the safety of the vaccine to the American public, he said.
"We don’t have a lot of tolerance for friendly fire. We know are fighting a war against COVID, but when our medical countermeasures injure people we don’t have a lot of tolerance for that and that tends to undermine vaccine confidence," he said. "We need to take steps to minimize or eliminate what could be friendly fire."
Healthcare providers who see patients presenting with a low platelet count or a blood clot should establish whether that patient has recently been vaccinated to inform diagnostic evaluation and management, Marks said.
Clinicians should watch for any signs or symptoms that can signify a clot within one to three weeks after the J&J/Janssen vaccine, according to the FDA. Those symptoms could include severe headache, abdominal pain, leg pain, or shortness of breath within three weeks after vaccination.
Flu-like symptoms, including headaches, are common mild side effects of the vaccines for a few days after vaccination, officials said.
"It would be more important if someone reported to an emergency room with a very severe headache or blood clots," Marks said.
Patients with this rare condition should be referred to physicians experienced in treating blood clots. The need for this specialized treatment is one reason the CDC and the FDA saw an urgent need to get the word out about this rare combination of side effects, officials said.