Johnson & Johnson pauses COVID-19 vaccine trial due to an unexplained illness

By Rachel Arthur

- Last updated on GMT

J&J started its phase 3 trials on September 23. Pic:getty/totojang
J&J started its phase 3 trials on September 23. Pic:getty/totojang

Related tags Johnson & johnson COVID-19 COVID-19 vaccine

Johnson & Johnson has paused dosing in all its COVID-19 vaccine candidate clinical trials – including its Phase 3 trial – due to an unexplained illness in a study participant.

Announcing the pause yesterday [October 12], Johnson & Johnson highlights that adverse events are an expected part of any clinical study, especially large ones. It has not released the nature or location of the illness: nor clarified if the illness is in the vaccine or placebo group.

The pause comes three weeks after Johnson & Johnson announced the start of its global Phase 3 trial for its vaccine candidate.

It follows a similar hold-up encountered by AstraZeneca with its coronavirus vaccine candidate (AstraZeneca paused global trials​ on September 6 due to an unexplained illness in one of the participants; trials have since restarted in the UK, Brazil and South Africa).

Vector vaccine 

Johnson & Johnson launched its Phase 3 trial​ for its vaccine candidate on September 23, setting out to enrol up to 60,000 people aged 18 and over in 215 sites in the US, Argentina, Brazil, Chile, Colombia, Mexico, Peru and South Africa.

Unlike a number of other frontrunners in the COVID-19 vaccine race, the Phase 3 trial is based on the vaccine requiring a single rather than double shot.

The Janssen COVID-19 vaccine candidate, JNJ-78436735 (also known as Ad.26.COV2.S), is a recombinant vector vaccine that uses a human adenovirus to express the SARS-CoV-2 spike protein in cells. It uses the company’s existing AdVac technology platform (used to develop and manufacture Janssen’s European Commission approved Ebola vaccine and construct its Zika, RSV, and HIV vaccine candidates).

As per Johnson & Johnson’s guidelines, the participant’s illness is being reviewed by the Ensemble Independent Data Safety Monitoring Board as well as the company’s internal clinical and safety physicians.

“Adverse events – illnesses, accidents, etc. - even those that are serious, are an expected part of any clinical study, especially large studies,”​ says Johnson & Johnson in a statement issued yesterday.

“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.

“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.

“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.”

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