Johnson and Johnson’s COVID-19 vaccine study has been suspended after participants developed an unexplained disease.

Research on Johnson and Johnson’s COVID-19 vaccine has been suspended because of an unexplained illness caused by a study participant,media Stat News reported. A document sent to outside researchers running the 60,000-patient clinical trial says the “pause rule” has been met, the online system used to register patients for research has been shut down, and the Data and Safety Monitoring Board, an independent committee that monitors patient safety in clinical trials, will be convened. The file was obtained by Stat News.

Johnson and Johnson's COVID-19 vaccine study has been suspended after participants developed an unexplained disease.

Stat News reported that Johnson and Johnson confirmed the suspension of the study, saying it was due to “an unexplained illness in one of the study participants.” The company declined to provide further details.

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

Johnson and Johnson stresses that so-called adverse events — disease, accidents and other adverse medical outcomes — are a predictable part of clinical research, and highlights the difference between research suspension and clinical shelving, a formal regulatory action that can last longer. The vaccine study is not currently on clinical hold. Johnson and Johnson says that while it usually communicates clinical reservations to the public, it does not usually inform the public that research is suspended.

The Data and Security Monitoring Committee (DSMB) met later on Monday to review the case. In such cases, Johnson and Johnson said, “it’s not always immediate to see whether participants with adverse events were receiving research therapy or a placebo.” “

While clinical trial suspensions are not uncommon — in some cases only for a few days — they are attracting much attention in the vaccine testing race against SARS-CoV-2, the virus that led to Covid-19. Given the size of the Johnson and Johnson trial, it’s not surprising that the study is suspended, and if the problem is solved, another could happen, said a source familiar with the study.

“If we do a study of 60,000 people, it’s a small village, ” the source said. “In a small village, there are a lot of medical incidents.”

On September 8th a major study into another Covid-19 vaccine being developed by AstraZeneta and Oxford University was shelved because of a suspected adverse reaction in a patient in the UK. The patient is believed to have transverse myitis. Vaccine research resumed about a week after it was suspended in the UK, and has since resumed in other countries. But in the United States, it is still on hold.

Johnson and Johnson began recruiting volunteers in its Phase 3 study on September 23. The researchers plan to recruit 60,000 participants in the United States and other countries.