Researchers running the 60,000 patient trial received a notice saying the "pausing rule has been met," Stat News reports.
The online patient-enrolling system was subsequently closed and a meeting for the patient safety monitoring board comprised of independent committee met Monday evening, the report says.
J&J -- based in New Brunswick -- declined to tell Stat News anything more than a study participant suffered an unexplained illness.
The company began enrolling participants in the Phase 3 study on Sept. 23.
Accidents, illnesses and other adverse medical outcomes were to be expected with the study, the company said.
Clinical trial pauses are reportedly not uncommon and some last less than a week, Stat News reports. The COVID-19 vaccine study is not currently under a clinical hold.
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