US health officials called for an immediate pause in use of Johnson & Johnson’s single-dose Covid-19 vaccine after six women who received it developed a rare and severe form of blood clotting.
The decision comes at a crucial juncture in the US vaccination effort, which has been gaining speed in recent weeks at the same time that a worsening outbreak driven by coronavirus variants is gripping the upper Midwest. And it is likely to heighten worry about vaccines around the world after similar issues caused delays in distribution of AstraZeneca Plc’s shot.
A type of brain blood clot called cerebral venous sinus thrombosis was seen with low levels of blood platelets in the women, who were all between the ages of 18 and 48, the US Centers for Disease Control and Prevention and Food and Drug Administration said on Tuesday in a joint statement.
“We are recommending a pause in the use of this vaccine out of an abundance of caution,” the CDC and the FDA said in the statement. “This is important, in part, to ensure that the health care provider community is aware of the potential for these adverse events and can plan for proper recognition and management due to the unique treatment required with this type of blood clot.”
More than 6.8 million doses of the J&J vaccine have been administered in the US through Monday, the agencies said.
The Biden administration has been seeking to accelerate vaccinations in recent weeks as new coronavirus variants heighten the risk that the pandemic could drag on. Officials expect 100 million doses of J&J’s vaccine to help cover all adults near the end of May.
The prospect that the pause could disrupt the US economic recovery weighed on financial markets on Tuesday, with futures trading indicating that the stock market was likely to open lower. Contracts tied to the S&P 500 were down roughly 0.23%.
J&J representatives didn’t immediately respond to a request for comment. The shares fell 3% in premarket US trading.
The decision could increase vaccine hesitancy, which is seen as a significant obstacle for health policy makers as they attempt to broaden immunisations. The J&J shot has been popular due to its single dose — vaccines made by Pfizer Inc.-BioNTech SE and Moderna Inc. require two doses spaced several weeks apart.
Many of the J&J doses in the US have been targeted to harder-to-reach populations through the federal government’s distribution program that targets pharmacies, federally qualified health centers and other locations.
The CDC will convene a meeting Wednesday of its Advisory Committee on Immunisation Practices to review the cases and assess their potential significance. The FDA will review the CDC assessment as it also investigates these cases, according to the statement.
The recommended pause may also further complicate the global vaccination push, coming just weeks after a vaccine relying on a similar approach and developed by AstraZeneca and the University of Oxford raised similar concerns in Europe. Clotting fears have prompted many countries to impose age restrictions on use of the Astra vaccine, which was co-developed with the University of Oxford.
J&J has recently begun shipments to the European Union. The bloc’s drugs regulator, the European Medicines Agency, didn’t immediately respond to a request for comment.
The EMA has previously said that it is assessing blood clots in people who received the J&J vaccine, after four serious cases of unusual clots accompanied by low blood platelets, one of which was fatal, emerged.
On Friday afternoon, FDA spokesperson Abby Capobianco said in an emailed statement that the agency hadn’t found a causal relationship with between the J&J vaccine and the six cases of thromboembolic events, and was continuing its assessment of the cases.
“Our analysis of the data will inform the potential need for regulatory action,” she said.
Asked Monday if further analysis had determined a casual relationship, the FDA declined to comment.