Johnson & Johnson pauses Covid vaccine trial after 'unexplained illness'

The pause includes the company’s phase 3 Ensemble trial and J&J said the participant’s illness is being reviewed and evaluated by the Ensemble independent data safety monitoring board and its internal clinical and safety physicians.

Johnson & Johnson, which did not disclose the nature of the illness, said it was important to have all the facts before sharing additional information.

It also pointed out that adverse events are an expected part of any clinical study, especially large studies and that a study pause is different to a regulatory hold and a standard component of a clinical trial protocol.

"Based on our strong commitment to safety, all clinical studies conducted by the Janssen Pharmaceutical Companies of Johnson & Johnson have prespecified guidelines," the company said.

"These ensure our studies may be paused if an unexpected serious adverse event (SAE) that might be related to a vaccine or study drug is reported, so there can be a careful review of all of the medical information before deciding whether to restart the study."

Evercore ISI said many questions remain, but that the trial design meant the participant who fell ill was healthy coming into the trial. It said the key next step will be whether data monitoring allows the trial to resume.