The US healthcare giant did not say when it would deliver any new doses or how many it would be able to supply. It is also unclear how many had been delivered prior to the stoppage.

The EMA is also requiring a warning label for the AstraZeneca vaccine. Both its and J&J’s are based on a viral vector (a chimpanzee virus and a human virus respectively), and both have been associated with incidences of unusual blood clots combined with low blood platelets.

In the US, health authority Centers for Disease Control (CDC) is widely expected to give the green light for the J&J restart there on Apr. 23. President Joe Biden’s pandemic adviser, top infectious disease expert Anthony Fauci, suggested this week that a warning label might be required. Parallel to the suspension, around 7 million people had been given the single dose nationwide.

In reviewing the J&J shot – the European agency was first to report the eight serious US cases of the rare blood clots associated with low levels of blood platelets, one fatal – the EMA said its risk assessment committee PRAC considered all currently available evidence.

Based on its study of the US cases, which all occurred in people under 60 years of age within 3 weeks after vaccination, mostly in women, the EU health authority said specific risk factors have not been identified. It is thought, however, that the vaccine may trigger an immune response leading to a heparin-induced-thrombocytopenia like disorder.

Some US health experts say they worry that the well publicized pause could discourage some people from getting the J&J shot, noting that numerous people in Europe have deliberately missed appointments in which AstraZeneca was listed as the vaccine to be administrated. The Anglo-Swedish drugmaker’s vaccine has not yet been approved in the US.

One of the constraints of the US distribution system is that people in underserved areas often have to travel long distances to get a second shot, so that a single-dose product could be an advantage.

Author: Dede Williams, Freelance Journalist