AstraZeneca, J&J say their COVID-19 vaccine trials back on track in US

AstraZeneca announced Friday that it has been cleared to restart its Phase III COVID-19 vaccine trial in the US. The company, which is co-developing AZD1222 with the University of Oxford, had paused global testing of the vaccine candidate early last month after a UK participant fell ill with what is believed to be transverse myelitis, and while the study has already started up again in some places, it remained on hold in the US pending an FDA probe.

Separately, Johnson & Johnson stated that it is "preparing to resume recruitment" in the US of a Phase III trial for its coronavirus vaccine candidate JNJ-78436735, suspended earlier this month due to an unexplained illness in a participant.

Neurological side effects

Regarding AstraZeneca's study, the drugmaker said "the FDA reviewed all safety data from trials globally and concluded it was safe to resume the trial." Prior to AstraZeneca releasing its statement, a report in The Wall Street Journal cited a person familiar with the matter as saying the FDA had completed its examination of two instances of a possible neurological side effect that emerged in two study participants who received AZD1222. Aside from the UK case that prompted the global study shutdown on September 6, CEO Pascal Soriot later revealed that there had been a pause in July as well, after a trial participant experienced neurological symptoms, although that turned out to be multiple sclerosis unrelated to the vaccine, and testing resumed.

According to the source cited in The Wall Street Journal, the FDA did not find that AZD1222 was responsible for either of the two cases, but nor could it rule out a potential link either. The source said the agency plans to require researchers to inform study subjects of the cases and monitor them for any related neurological events, such as numbness. Testing on AZD1222 had already gotten back on track in countries such as the UK, India, South Africa, Japan and Brazil, where recently one participant died, although that person is believed not to have received the vaccine, and the study has been allowed to continue.

'No clear cause' found

As for Johnson & Johnson's ENSEMBLE trial, the company said there was a "thorough evaluation of a serious medical event experienced by one study participant," but that "no clear cause has been identified." An article that appeared in the Washington Post prior to the company's statement, cited two sources as saying the volunteer in question had suffered a stroke, but that an independent committee concluded it was not related to the JNJ-78436735 vaccine.

Johnson & Johnson noted that the trial's independent Data Safety and Monitoring Board "has recommended resuming trial recruitment." The company said it is working on preparations to resume the study in the US around the start of next week, while discussions "are progressing" with other regulators around the world to proceed with the clinical trial programme. Chief scientific officer Paul Stoffels also indicated that Johnson & Johnson remains on track to produce data from the ENSEMBLE trial on the vaccine's effectiveness by the end of 2020 or early 2021.

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