Pharmaceutical giant Johnson & Johnson on Monday night announced that it had paused its late-stage COVID-19 vaccine trial after an “unexplained illness” was reported in a participant. 

“Adverse events – illnesses, accidents, etc. — even those that are serious, are an expected part of any clinical study, especially large studies,” the company said in a statement when announcing the temporary halt. 

The pause, which was first reported by the health news site STAT, come after the company began the Phase 3 trial of its vaccine in September. 

The pause, which was first reported by the health news site STAT, come after the company began the Phase 3 trial of its vaccine in September. 
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No details on the illness were revealed, and it’s not currently clear if the illness is related to the shot or was a coincidence. It’s also not clear if the volunteer had received the vaccine or the placebo. 

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

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The pause, which was first reported by the health news site STAT, comes after the company began the Phase 3 trial of its vaccine in September. 

The temporary halt is not the first to occur in the race to find a safe and effective vaccine to protect against COVID-19. In fact, the pause is the second such hold to occur among several vaccine candidates that have reached large-scale final tests in the U.S.

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Final-stage testing of a vaccine made by AstraZeneca and Oxford University remains on hold in the U.S. as officials examine whether an illness in its trial poses a safety risk. That trial was stopped when a woman developed severe neurological symptoms consistent with transverse myelitis, a rare inflammation of the spinal cord, the company has said. That company's testing has restarted elsewhere.

Johnson & Johnson was aiming to enroll 60,000 volunteers to prove if its single-dose approach is safe and protects against the coronavirus. Other vaccine candidates in the U.S. require two shots.

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The Associated Press contributed to this report.