This photo taken on October 12 shows a health worker taking a swab from a middle school student to be tested for Covid-19, as part of a mass testing program following a new coronavirus outbreak in Qingdao, in China's eastern Shandong province.

This September 2020 photo from Johnson & Johnson shows a single-dose Covid-19 vaccine being developed by the company. Cheryl Gerber / Courtesy Johnson & Johnson via AP

Johnson & Johnson announced Tuesday that the company learned of the “unexplained disease” that caused it to suspend its Phase 3 coronavirus vaccine study in the US on Sunday and immediately notified Data and Safety Monitoring Board (DSMB) that monitors clinical trial developments.

The drug company said it did not know whether the sick volunteer received the vaccine or the placebo.

“We are now awaiting further medical information and evaluations, which we will then forward to the DSMB for further independent recommendations,” said Mathai Mammen, global director of research and development at Johnson & Johnson subsidiary Janssen, on Tuesday at Company earnings report for the third quarter.
“It is by no means uncommon for unexpected diseases to appear in large studies over their duration,” said Mammen. In some cases these are called Serious Adverse Events or SAEs and may or may not have anything to do with the drug or vaccine being studied, ”Mammen said.

Mammen said the company “currently has very little information” about the disease that interrupted the process, but said the DSMB has submitted a number of specific questions to answer.

As of Tuesday morning, the study will remain blinded, which means that participants and those who will give the vaccine candidates will not know whether they will be receiving the vaccine or a placebo. Mammen added that the DSMB has the option to unblind the study to investigate the unexplained disease if necessary.

Johnson & Johnson announced on Monday that the clinical trial would be suspended, making it the second phase 3 coronavirus vaccine study to be suspended.

AstraZeneca’s vaccine study was suspended last month due to a neurological complication in a volunteer in the UK. While the trial has resumed there and in other countries, it remains on hold in the US while the US Food and Drug Administration is investigating.