Pharmaceutical giant Johnson & Johnson paused its 60,000-person coronavirus vaccine trial Monday after a participant fell ill with undisclosed symptoms, making it the second large U.S. vaccine trial to halt inoculations as investigators probe whether the sickness may be linked to the vaccine.
Experts say the pause by Johnson & Johnson and an ongoing hold on the AstraZeneca trial in the United States demonstrate the system in place to protect the safety of participants is working as intended. But the intense scrutiny of the vaccine trials, combined with unprecedented efforts to speed up vaccine development, mean that the lack of transparency around possible adverse events could unintentionally help foster distrust of the vaccine effort.
“I certainly think it’s standard to limit information until more details are known,” said an investigator for the Johnson & Johnson trial, who spoke on the condition of anonymity to discuss the issue frankly. The investigator said the company had not provided additional information to experts leading the trials about the reason for the pause.
“We need to eventually know more details if they expect people to continue to enroll at the rates they expect,” the investigator added. “We are already seeing slower rates of enrollment due to multiple factors, but one must be the way AstraZeneca has handled their safety issue.”
The AstraZeneca trial was paused in early September due to a neurological symptom in a British participant, the second such incident to stop the trial. The pause was praised at the time as a sign the system was working, but the trial was quickly restarted in other countries, with minimal information disclosed about the nature of the event. It continues to be on hold by the Food and Drug Administration pending a deeper investigation, which raises questions about why the U.S. review is taking so much longer than that in the rest of the world.
“FDA continues to review safety information, and we’ll just have to see over the next week or so where that turns out,” Paul Mango, deputy chief of staff for policy at the Department of Health and Human Services said at a briefing on Friday.
Johnson & Johnson disclosed “an unexplained illness in a study participant” in a news release Monday evening. Company spokesman Jake Sargent declined to offer further details of the illness, including whether it had happened in a person given the vaccine or a placebo. The company distinguished between its own voluntary pause and a hold, when regulatory experts stop a trial.
Johnson & Johnson disclosed in a statement that an independent board of experts was now examining its event. It said the pause was triggered by rules that “ensure our studies may be paused if an unexpected serious adverse event 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 cited the need to protect the participant’s privacy before providing more information.
“The fact that the trials are paused demonstrates that safety is being held in high regard, a fact in which we should take comfort,” said David Benkeser, a biostatistician at Emory University’s Rollins School of Public Health. “A key thing for the public to understand is that the recommendation of whether to continue the trial comes from the independent data safety and monitoring board, based on the opinions of independent medical experts. We want these bodies to act carefully and deliberately, which can take some time.”