(BBC) – Johnson & Johnson has paused its Covid vaccine trial to investigate why one participant in the study fell ill.
The company said an independent review would check if the person’s unexplained symptoms were related to the jab.
It has suspended recruitment to the phase three trial as a precaution.
It said in large trials, with tens of thousands of volunteers, it was to be expected that some may become unwell during the study period.
The company said that for privacy reasons, it could not give more details about the participant.
“We’re also learning more about this participant’s illness, and it’s important to have all the facts before we share additional information,” it said in a statement
It is not the first Covid vaccine trial to be suspended – a participant in the UK’s Oxford University study had an unexplained illness too, but it has since been deemed safe to resume, except for in the US where regulators are still in discussions with manufacturer Astra Zeneca.