Johnson & Johnson COVID-19 Vaccine Paused After Reports of Cerebral Venous Thrombosis

This article originally appeared on ContagionLive, a sister publication of NeurologyLive.

Six cases of cerebral venous thrombosis have been reported in women aged 18 to 48 who received Johnson & Johnson's Janssen COVID-19 vaccine, causing the US Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) to pause administration at federal sites pending a larger investigation.

Reports of the rare blood clotting disorder were recorded 6 to 16 days following administration of the one-shot adenovirus Ad26.COV2.S vaccine. As of Tuesday morning, 1 woman with the condition has died and a second woman in Nebraska is hospitalized and in critical condition.

Based on this, the federal agencies have advised that states distributing the vaccine also pause their operations.

"We are aware of an extremely rare disorder involving people with blood clots in combination with low platelets in a small number of individuals who have received our COVID-19 vaccine. The United States Centers for Disease Control (CDC) and Food and Drug Administration (FDA) are reviewing data involving six reported U.S. cases out of more than 6.8 million doses administered," Johnson & Johnson said in a statement. "In addition, we have been reviewing these cases with European health authorities. We have made the decision to proactively delay the rollout of our vaccine in Europe."

The pharmaceutical company went on to say that "people who have received our COVID-19 vaccine and develop severe headache, abdominal pain, leg pain, or shortness of breath within three weeks after vaccination should contact their health care provider."

The FDA and CDC investigators intend to collaborate on assessment of possible links between the Janssen vaccine and cerebral venous thrombosis in order to discern whether the company’s Emergency Use Authorization (EUA) should continue as-is or become limited.

The FDA reiterated the importance of an indefinite pause during this investigation in a statement shared on Twitter Tuesday morning.

"This is important to ensure that the health care provider community is aware of the potential for these adverse events and can plan due to the unique treatment required with this type of blood clot," they wrote.

The CDC’s Advisory Committee on Immunization Practices (ACIP) will hold an emergency meeting on the matter this Wednesday, according to The New York Times.

Per the CDC, more than 6 million people in the US have received Janssen’s vaccine thus far, and another 9 million doses have been shipped to different states.

Comparatively, Pfizer-BioNTech and Moderna have delivered 23 million-plus doses weekly of their two-dose mRNA vaccines to the US, comprising a significant majority of the US’ vaccine distribution. No significant safety concerns have emerged from either product.

Just last month, the Biden administration announced the acquisition of another 100 million doses of Ad26.COV2.S from Janssen, to be delivered in the latter half of 2021.

And in early April, Janssen announced delays in manufacturing at its Baltimore plant due to the inadvertent mixing of vaccine ingredients. The error resulted in the loss of up to 15 million doses.