Blood clot cases shelve J&J vaccine

As scientists examine possible links between Johnson & Johnson's COVID-19 vaccine and severe cases of blood clots, a panel of outside experts will meet Wednesday to review the matter for the Centers for Disease Control and Prevention while the Food and Drug Administration will conduct an investigation into the cause of the clots and low platelet counts among women who got the vaccine.

The CDC and FDA on Tuesday recommended a pause in the use of J&J's vaccine after finding that six women between the ages of 18 and 48 years had developed blood clots.

One woman died, and a second woman in Nebraska has been hospitalized in critical condition. The clots developed six to 13 days after vaccination. The women also had in their blood low counts of platelets, which help with clotting.

The blood clotting that the women developed, known as cerebral venous sinus thrombosis, is extremely rare. All of them developed the condition within about two weeks of vaccination, and government experts are concerned that an immune system response triggered by the vaccine was the cause.

"We are recommending a pause in the use of this vaccine out of an abundance of caution," Dr Peter Marks, director of the FDA's Center for Biologics Evaluation and Research, and Dr Anne Schuchat, principal deputy director of the CDC, said in a joint statement. "Right now, these adverse events appear to be extremely rare."

J&J said in a statement: "We are aware that thromboembolic events including those with thrombocytopenia have been reported with Covid-19 vaccines. At present, no clear causal relationship has been established between these rare events and the Janssen COVID-19 vaccine." Janssen is the name of J&J's division that developed the vaccine.

Authorities in Ohio, New York, Connecticut, Massachusetts, Maryland, Georgia and Virginia said Tuesday that they would pause use of the vaccine.

The Biden administration plans to deliver enough vaccine to be able to inoculate all 260 million adults in the US by the end of May. Now federal officials expect there will only be enough to cover fewer than 230 million adults.

J&J's vaccine was the third authorized for use in the US. It uses the same technology as a vaccine from AstraZeneca PLC and the University of Oxford, not yet authorized in the US, which also has been linked to rare cases of blood clots.

Nearly 7 million people in the US have received J&J's one-dose shot so far, the vast majority experiencing zero or mild side effects, and roughly 9 million more doses have been shipped out to the states, according to data from the CDC.

Most of the nation's vaccine supply comes from Pfizer-BioNTech and Moderna, which together deliver more than 23 million doses a week of their two-shot vaccines. There have been no significant safety concerns about either of those vaccines.

The J&J vaccine received emergency use authorization from the FDA in late February with the hope that its single-dose and relatively simple storage requirements would speed vaccinations. Yet the shot makes up only a small fraction of the doses administered in the US, as J&J has been plagued by production delays and manufacturing errors at the Baltimore plant of a contractor.

Last week J&J took over the facility to scale up production in hopes of meeting its commitment to the US government of providing about 100 million doses by the end of May.

Until now, concern about blood clots has centered on the vaccine from AstraZeneca, which hasn't yet received authorization in the US.

Last week, European regulators said they found a possible link between the shots and a very rare type of blood clot that occurs together with low blood platelets, one that seems to occur more in younger people. Several countries have imposed limits on who can receive the vaccine. The UK recommended that people under 30 be offered alternatives.