Johnson & Johnson (J&J) has temporarily paused all dosing in its COVID-19 vaccine candidate trials, including its Phase III Ensemble trials, due to an unexplained illness in a study participant.

The company says that the participant’s illness is being reviewed and evaluated by an independent data safety monitoring board as well by the company’s internal clinical and safety physicians. The company noted that a study pause, in which recruitment or dosing is paused by the study sponsor, is a standard component of a clinical trial protocol.

“Adverse events—illnesses, accidents, etc.—even those that are serious, are an expected part of any clinical study, especially large studies,” said the company in an October 12, 2020 statement. “Based on our strong commitment to safety, all clinical studies conducted by the Janssen Pharmaceutical Companies of Johnson & Johnson have prespecified guidelines. These ensure our studies may be paused if an unexpected serious adverse event (SAE) that might be related to a vaccine or study drug is reported, so there can be a careful review of all of the medical information before deciding whether to restart the study.”

The company further explained in its statement that “SAEs are not uncommon in clinical trials, and the number of SAEs can reasonably be expected to increase in trials involving large numbers of participants. Further, as many trials are placebo-controlled, it is not always immediately apparent whether a participant received a study treatment or a placebo.”

J&J initiated its Ensemble Phase III trial, a large-scale multi-country clinical trial last month (September 2020). The trial was set to enroll up to 60,000 volunteers to study the safety and efficacy of a single vaccine dose versus placebo in preventing COVID-19.

J&J is one of several companies advancing COVID-19 vaccine candidates and is the second one to recently pause clinical trials due to an unexpected illness in a study participant. Last month (September 2020), AstraZeneca paused clinical trials for its COVID-19 vaccine, AZD1222, to allow an independent committee to review the safety data of a single event of an unexplained illness that occurred in a Phase III trial in the UK. Since then (as of October 2, 2020), regulators in Japan, the UK, Brazil, South Africa, and India have deemed the trials are safe to resume. The company says it continues to work with the US Food and Drug Administration to facilitate review of the information needed to make a decision regarding resumption of the US trial.

Source: Johnson & Johnson