Johnson & Johnson pauses its coronavirus vaccine trials as volunteer falls ill

Johnson & Johnson says it has paused its coronavirus vaccine trial because one of the volunteer participants has an unexplained illness.

The company began a Phase 3 trial for its experimental coronavirus vaccine in September and intends to enroll as many as 60,000 participants in the United States and abroad.

The participant's illness is being reviewed by an independent data-safety monitoring board, the company said Monday.

Johnson & Johnson's vaccine development guidelines account for the possibility of side effects developing out of its study and pre-specify procedures for when they do occur.

The company's policy recommendations "ensure our studies may be paused if an unexpected serious adverse event 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," according to a statement from the developer.

Johnson & Johnson executives say their Phase 3 trial could begin yielding results by late 2020 or early 2021, followed shortly by the authorization of shots for the public.

The company's vaccine used a weakened version of a common cold virus, with a goal of delivering genetic instructions into the body to teach cells to create a protein similar to the one that coats the outside of the coronavirus. The body's immune system will then, hopefully, learn to create a line of defense against the virus, should a person be exposed to it. 

Johnson & Johnson is not the first company battling for a coronavirus vaccine to put its process on hold. Last month, AstraZeneca paused its vaccine trial over a similar safety concern. The portion of the study taking place in the U.K. has since resumed, but a large part of the U.S. study remains on hold. 

The independent board reviewing the Johnson & Johnson case will now work to determine if the individual's side effects can be determined to be related to the vaccine.