Update: J&J COVID vaccine rollout paused as clot concerns spread

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US health authorities have recommended pausing dosing with Johnson & Johnson's COVID-19 vaccine as they investigate cases of blood clots also observed in some people taking the AstraZeneca shot. 

The EU and South Africa meanwhile have also said they will suspend the rollout of the shot while the probe is ongoing.

Yesterday, the FDA said there had been reports of six cases of cerebral venous sinus thrombosis (CVST) associated with low blood platelet counts (thrombocytopenia) out of more than 6.8 million doses of the Janssen vaccine.

All occurred among women between the ages of 18 and 48, with symptoms occurring between six and 13 days after vaccination.

The Centers for Disease Control and Prevention (CDC) will hold an advisory committee meeting tomorrow to review the cases, and in the meantime the FDA says it is recommending a pause in the use of the vaccine "out of an abundance of caution".

The regulator stressed that the side effects appear to be extremely rare, but recommended that anyone dosed with the shot who develop symptoms including severe headache, abdominal pain, leg pain, or shortness of breath within three weeks should contact their doctor.

The pause "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," said the FDA and CDC joint statement.

The one-dose vaccine – made by J&J's Janssen subsidiary – is also being investigated by regulators in Europe, and was discussed by the EMA's Pharmacovigilance Risk Assessment Committee (PRAC) last week along with AZ's jab, which is already subject to some age-related restrictions in some countries.

Last week, PRAC said it had found four serious cases of unusual blood clots with the Janssen vaccine, including one that proved fatal. One of those cases was identified in a clinical trial, and resulted in the study being placed under a temporary suspension by the FDA last October.

The latest PRAC figures on the AZ vaccine identified 62 cases of CVST and another 24 cases of another blood clot affecting the abdomen – splanchnic vein thrombosis – out of 25 million doses, with 18 deaths.


The J&J vaccine is currently only used in the USA, under an emergency use authorisation, but was approved by the EMA on 11 March.

"The vaccine rollout has not started yet in any EU member state but is expected in the next few weeks," said the EMA last Friday.

The EU has been anticipating the arrival of the J&J vaccine to help support its COVID-19 vaccination programme, which has been rolling out slowly due in part to delays in shipments of the approved vaccine candidates, including shots from AZ, Pfizer/BioNTech and Moderna.

J&J has issued a statement saying that safety was its top priority, and that it had shared all adverse event reports for its vaccine with health authorities.

"We are aware that thromboembolic events including those with thrombocytopenia have been reported with COVID-19 vaccines," it continued. "At present, no clear causal relationship has been established between these rare events and the Janssen COVID-19 vaccine."