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

• 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.