Janssen COVID-19 Vaccine Expected to be Temporarily Discontinued

Because of 6 US cases of rare blood clot disorders that it may have caused, the Janssen Pharmaceuticals COVID-19 vaccine will not be administered at federal sites, according to a ruling expected to be made by the US Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC). The agencies want to investigate exactly what’s going on.

The federal agencies will announce the decision for an immediate pause of the one-shot adenovirus Ad26.COV2.S while advising states distributing the product to consider doing the same, as 6 women aged 18-48 years old reported cerebral venous thrombosis, an extremely rare disorder associated with blood clotting, 6-16 days following their vaccination.

As of Tuesday morning, 1 woman afflicted with the condition has died, and a second woman in Nebraska is hospitalized and in critical condition.

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.

This story originally appeared in Contagion®.