The company said in a statement Monday night that illnesses, accidents and other so-called adverse events “are an integral part of any clinical study, especially large studies,” but its doctors and a safety watch group would try to determine what could have caused the disease.
The break is at least the second of its kind to occur among several vaccines that have reached full scale final testing in the United States.
The company declined to disclose further details about the illness, citing the participant’s privacy.
Temporary stoppages from major medical studies are relatively common. Few of these are made public in typical drug trials, but the work of manufacturing a vaccine for the coronavirus has raised the stakes of these kinds of complications.
Companies are required to investigate any serious or unexpected reactions that occur during drug testing. Since such tests are performed on tens of thousands of people, some medical issues are a coincidence. In fact, one of the first steps the company has announced is to determine whether the person has received the vaccine or a placebo.
The stop was first reported by the STAT health information site.
End-phase testing of a vaccine made by AstraZeneca and the University of Oxford remains on hold in the United States as authorities examine whether a disease in its trial poses a safety risk. That trial was stopped when a woman developed severe neurological symptoms consistent with transverse myelitis, a rare inflammation of the spinal cord, the company said. This company’s testing has been resumed elsewhere.
Johnson & Johnson aimed to recruit 60,000 volunteers to prove whether its single-dose approach is safe and protects against the coronavirus. Other vaccine candidates in the United States require two injections.