The New Jersey-based company – which sought 60,000 volunteers mostly over 60 – didn’t describe the illness or identify the patient in any way.
“We must respect this participant's privacy,” J&J said in a statement. “We're also learning more about this participant's illness, and it's important to have all the facts before we share additional information.”
J&J said it would provide transparent updates throughout the development of the randomized, double-blind, placebo-controlled trial, which entered Phase 3 three weeks ago.
It’s the second Phase 3 trial to be paused in the United States of a total of four in the advanced stage.
AstraZeneca put the brakes on theirs last month because of a neurological complication in a volunteer in Britain.
J&S said its situation was being reviewed and evaluated by a monitoring board, as well as its internal clinical and safety physicians, to determine whether the illness is linked to the vaccine or merely a coincidence.
"Adverse events -- illnesses, accidents, etc. -- even those that are serious, are an expected part of any clinical study, especially large studies," the statement said.
Experts estimated that a vaccine could be approved for emergency use sometime in November or December but wouldn’t commit to the possibility of it coming before the Nov. 3 national elections.
Others have said not to expect one until sometime between March and May.
A total of 42 coronavirus vaccines are in human trials, with 151 others in development, according to the World Health Organization.
"A study pause, in which recruitment or dosing is paused by the study sponsor, is a standard component of a clinical trial protocol," Johnson & Johnson said.
"Based on our strong commitment to safety, all clinical studies conducted by the Janssen Pharmaceutical Companies of Johnson & Johnson have prespecified guidelines,” the company added. “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.”
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