Coronavirus vaccine
Coronavirus vaccineiStock

The study of Johnson & Johnson’s COVID-19 vaccine has been paused due to an unexplained illness in a study participant, the STAT news website reported on Monday.

A document sent to outside researchers running the 60,000-patient clinical trial states that a “pausing rule” has been met, that the online system used to enroll patients in the study has been closed, and that the data and safety monitoring board — an independent committee that watches over the safety of patients in the clinical trial — would be convened. The document was obtained by STAT.

Contacted by STAT, J&J confirmed the study pause, saying it was due to “an unexplained illness in a study participant.” The company declined to provide further details.

“We must respect this participant’s privacy. We’re also learning more about this participant’s illness, and it’s important to have all the facts before we share additional information,” the company said in a statement.

J&J emphasized that so-called adverse events — illnesses, accidents, and other bad medical outcomes — are an expected part of a clinical study, and also emphasized the difference between a study pause and a clinical hold, which is a formal regulatory action that can last much longer. The vaccine study is not currently under a clinical hold. J&J said that while it normally communicates clinical holds to the public, it does not usually inform the public of study pauses.

Last month, AstraZeneca paused a late-stage trial of its COVID-19 vaccine after a suspected serious adverse reaction in a study participant. The trial resumed several days later.

Moderna and the Pfizer/BioNTech alliance have also been working on a vaccine for the virus.

US President Donald Trump recently estimated that a vaccine for coronavirus may be produced ahead of the US presidential election on November 3.