US Regulators Push to Pause Johnson & Johnson Vaccine Over Blood Clots

There have been six instances of blood clots among the more than 6 million who’ve gotten the single-shot vaccine, but that’s enough for two federal agencies to grind administration of it to a halt.

Vials of Johnson & Johnson Covid-19 vaccine in the pharmacy of National Jewish Hospital for distribution in east Denver on March 6. (AP Photo/David Zalubowski, File)

WASHINGTON (CN) —  The Food and Drug Administration and Centers for Disease Control and Prevention recommended a pause Tuesday in administering Johnson & Johnson vaccines following a handful of cases in which women who received the shot experienced severe blood clots.

Peter Marks, director of the FDA’s center for biologics evaluation and research, and Anne Schuchat, principal deputy director of the CDC, said the pause was out of “an abundance of caution,” in a joint statement Tuesday. Roughly 6.8 million doses of the J&J vaccine have been distributed in the U.S. since the jab received unanimous approval from an FDA panel at the end of February — and just six cases of individuals experiencing “a rare and severe type of blood clot” after vaccination have been reported, according to the announcement.

Janet Woodcock, acting FDA commissioner, stressed at a press conference Tuesday morning that while the events appear to be extremely rare, Covid-19 vaccine safety is a top priority for the federal government. “We take all reports of adverse events following vaccination, very seriously,” she said.

Woodcock indicated that she expects the pause to only be a matter of days while the matter is investigated but the exact timeframe will depend on what investigators learn.

Following the FDA and CDC’s recommendation, Johnson & Johnson announced Tuesday it would delay the rollout of its vaccine in Europe; it was planning to ship hundreds of thousands of doses in the next few weeks.

“We have been reviewing these cases with European health authorities,” the company said. “We have made the decision to proactively delay the rollout of our vaccine in Europe.”

The European Medicines Agency, which regulates food and drugs for the European Union, said in a statement Friday that it had flagged the J&J vaccine for investigation due to reports of blood clots in recipients.

Of the six cases seen in the United States, “one case was fatal and one patient is in critical condition,” Marks said at the Tuesday press conference.

“We don’t have a definitive cause,” he said, “but the probable cause that we believe may be involved here — we can speculate — is a similar mechanism that may be going on with other the other adenovirus vectored vaccines: an immune response that occurs very, very rarely. After some people received the vaccine, and that immune response, leads to activation of the platelets and these extremely rare blood clots.”

People walk in to get their Covid-19 vaccine at the Baldwin Hills Crenshaw Plaza in Los Angeles on April 1. (AP Photo/Damian Dovarganes)

Marks acknowledged Tuesday at the conference that the immune response to the J&J vaccine is very similar to that seen in the AstraZeneca vaccine, which was briefly suspended last month in several major European nations for similar reports of blood clots. The vaccines are formulated similarly, he said, noting the AstraZeneca vaccine uses a chimpanzee adenovirus vaccine vector, while the J&J vaccine uses a human adenovirus vaccine vector to carry Covid-19 fighting instructions to the vaccine recipient’s immune system.

“The issue here with these types of blood clots, is that if one administers the standard treatments that we as doctors have learned to give for blood clots. One can actually cause tremendous harm, or the outcome can be fatal,” Marks said. “So one needs to make sure that providers are aware that if they see people who have low blood platelets, or if they see people who have blood clots, they need to inquire about a history of recent vaccination, and then act accordingly.”

As of Tuesday, the globe is approaching 137 million infections from Covid-19. The United States has seen more than 31 million infections and 562,718 deaths. More than 120 million Americans, some 36.4% of the U.S. population, have had at least one dose of vaccine, and 74 million (22.3%) are fully vaccinated.

All six cases of blood clots that the FDA and CDC are investigating happened among women between the ages of 18 and 48, who began to experience symptoms 6 to 13 days after vaccination. The blood clots in question were seen in combination with low levels of blood platelets. This kind of blood clot, Marks and Schuchat said Tuesday, requires special treatment and cannot be treated with heparin, the typical go-to anticoagulant drug.

“In this setting, administration of heparin may be dangerous, and alternative treatments need to be given,” Marks and Schuchat said, explaining that investigating the cases will allow the FDA and CDC to offer proper guidance to the health care community in case of adverse effects. 

The FDA and CDC advise those who have received the Johnson & Johnson vaccine and experienced severe headaches, abdominal pain, leg pain or shortness of breath three weeks after vaccination to contact their health providers.

Schuchat acknowledged at the press conference Tuesday morning that this announcement may make people who have already gotten the J&J vaccine concerned. 

“For people who got the vaccine, more than a month ago, the risk for them is very low at this time,” she said. “For people who recently got the vaccine in the last couple of weeks, they should be aware, to look for any symptoms.”

Woodcock indicated Tuesday that any particular subgroups that are more at-risk for J&J complications will be identified by the federal regulators’ review. 

B cells release antibodies to bind to the virus that creates Covid-19. (Image courtesy of AstraZeneca via Courthouse News)

Johnson & Johnson, which developed the vaccine through its Janssen division, said the science is on its side. “We are aware that thromboembolic events including those with thrombocytopenia have been reported with Covid-19 vaccines,” the company said in a statement. “At present, no clear causal relationship has been established between these rare events and the Janssen Covid-19 vaccine.”

As compared to the other two vaccines against the novel coronavirus approved in America, Johnson & Johnson’s candidate was touted for requiring just one dose and its ability to be stored at normal refrigerator temperatures. Pfizer and Moderna’s vaccines both need to be kept on dry ice, creating logistical issues when it comes to shipping and storage.

The CDC has scheduled a Wednesday meeting for its Advisory Committee on Immunization Practices to further review these cases and assess their potential significance. The FDA will then review this panel’s analysis.

Marks said Tuesday that he does not expect the J&J pause to affect President Joe Biden’s goal of vaccinating 200 million Americans in his first 100 days of office. 

“This temporary pause is hopefully not going to have a large adverse effect on making those goals in a timely manner if at all,” Marks said.

Though the agencies termed their announcement as a recommendation for practitioners, no federally run vaccination site is expected to administer the vaccine pending the new study. State health officials are urged to heed this guidance.

Schuchat acknowledged Tuesday that the clotting events with low platelet counts have not been seen in the Pfizer and Moderna vaccines, and that those who have been scheduled to receive these vaccines should keep their appointments.

“Our partners will be working to reschedule people who have the J&J vaccine appointments in the days ahead,” she said. “This may be a bit bumpy.”

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