T he study of Johnson & Johnson’s Covid-19 vaccine has been paused due to an unexplained illness in a study participant.
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.
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“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.
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The data and safety monitoring board, or DSMB, convened late Monday to review the case. J&J said that in cases like this “it is not always immediately apparent” whether the participant who experienced an adverse event received a study treatment or a placebo.
Though clinical trial pauses are not uncommon — and in some cases last only a few days — they are generating outsized attention in the race to test vaccines against SARS-CoV-2, the virus that causes Covid-19.
Given the size of Johnson & Johnson’s trial, it’s not surprising that study pauses could occur, and another could happen if this one resolves, a source familiar with the study said.
“If we do a study of 60,000 people, that is a small village,” the source said. “In a small village there are a lot of medical events that happen.”
On Sept. 8, a large study of another Covid-19 vaccine being developed by AstraZeneca and Oxford University was put on hold because of a suspected adverse reaction in a patient in the United Kingdom. It’s believed that the patient had transverse myelitis, a spinal cord problem. Studies of the vaccine resumed roughly a week after it was paused in the United Kingdom, and have since been restarted in other countries as well. It remains on hold, however, in the United States.
Johnson & Johnson began enrolling volunteers in its Phase 3 study on Sept. 23 . Researchers planned to enroll 60,000 participants in the United States and other countries.