US pauses rollout of J&J’s COVID-19 vaccine amid reports of rare blood clots

The US Food and Drug Administration (FDA) and Centers for Disease Control & Prevention (CDC) have issued a joint statement today recommending a pause on the rollout of Johnson & Johnson’s (J&J) COVID-19 vaccine.

The pause comes following six reported cases in the US of a rare and severe type of blood clot – known as cerebral venous sinus thrombosis (CVST) – observed in individuals after receiving the vaccine. In these cases, the rare blood clot type was seen in combination with low levels of blood platelets, known as thrombocytopenia.

As of 12 April, over 6.8 million doses of the J&J jab have been administered in the US.

The CDC is set to convene a meeting of the Advisory Committee on Immunization Practices (ACIP) on Wednesday to review the cases and assess their ‘potential significance’, while the FDA will review the analysis and also investigate the cases, the regulatory agency said in a tweet.

The FDA added that the pause is due to ‘an abundance of caution’ as it reviews the blood clot cases.

‘Right now, these adverse events appear to be extremely rare. COVID19 vaccine safety is a top priority for the federal government, and we take all reports of health problems following COVID-19 vaccination very seriously,’ the FDA said in the statement.

According to The New York Times, all six cases of rare blood clot events occurred in women aged 18 to 48 who had had the J&J vaccine.

Health officials in the US are reportedly concerned that clinicians may not be trained to identify the rare disorder, with the FDA and CDC saying in their joint statement that the ‘treatment of this specific type of blood clot is different from the treatment that might typically be administered’.

‘Usually, an anticoagulant drug called heparin is used to treat blood clots. In this setting, administration of heparin may be dangerous, and alternative treatments need to be given,’ they added.

The European Medicines Agency’s (EMA) Pharmacovigilance Risk Assessment Committee (PRAC) has also started a review into reports of people developing blood clots after receiving the J&J COVID-19 vaccine.

This includes four ‘serious cases of unusual blood blots with low blood platelets’ - one occurred in a clinical trial and three occurred during the US rollout of the vaccine.

‘These reports point to a ‘safety signal’, but it is currently not clear whether there is a causal association between vaccination with COVID-19 Vaccine Janssen and these conditions,' said the EMA.