Johnson & Johnson pauses COVID-19 vaccine study due to "unexplained illness" in patient

Johnson & Johnson announced Monday has paused a study of its COVID-19 vaccine due to an "unexplained illness in a study participant.

Situational awareness: "This is the normal process. This doesn't mean the illness is related to the vaccine. But these things need to get investigated by an independent committee. Happens in many Phase III trials," Florian Krammer, a professor at School of Medicine at Mount Sinai, noted on Twitter.

• The AstraZeneca COVID-19 vaccine study was put on hold in early September after a study participant in the United Kingdom had a suspected adverse reaction. The study resumed in the U.K. roughly a week later, but remains on hold in the U.S., per STAT.
• Johnson & Johnson emphasized its study was paused and not under a "clinical hold," which STAT noted is "a formal regulatory action that can last much longer."
• The company noted in its statement that "it is not always immediately apparent" if the patient who became sick took the drug or a placebo.

The state of play: Johnson & Johnson began Phase III of its trial on Sept. 23, with the goal of enrolling 60,000 patients.

• It was the 4th vaccine in the U.S. to enter Phase 3.

Go deeper: Where the vaccine race stands in the U.S.

Editor's note: This article has been updated to include Johnson & Johnson's statement.