The FDA is looking into whether they should follow their UK counterparts in allowing a Phase III study of AstraZeneca's COVID-19 vaccine to resume after it had been temporarily suspended last week when a trial participant in the UK was said to have suffered spinal cord inflammation. AstraZeneca announced on September 12 that clinical trials of its AZD1222 candidate, which is being co-developed with the University of Oxford, have started up  again in the UK after regulators there determined that it would be safe to do so.
However, a report citing sources familiar with the matter suggested that testing would remain halted in the US pending an FDA investigation into the UK case that had led to the pause in the first place. The sources indicated that enrollment of new patients and other procedures for the pivotal US trial, which launched earlier this month, were being rescheduled until at least the middle of this week. The FDA has declined to comment on how long it would take before it decides whether to move forward.
Meanwhile, the US National Institutes of Health (NIH) is "in the planning stages" of its own investigation into the case, according to Avindra Nath, leader of viral research at the agency's National Institute for Neurological Disorders and Stroke. "The highest levels of NIH are very concerned," Nath said, adding that AstraZeneca "need[s] to be more forthcoming with a potential complication of a vaccine which will eventually be given to millions of people…We would like to see how we can help, but the lack of information makes it difficult to do so."
According to Nath, the NIH has yet to receive tissue or blood samples from the UK trial participant that sparked the study pause. US scientists could analyse samples from other vaccinated participants to see whether any of the antibodies they generated in response to the coronavirus also attack brain or spinal cord tissue, although Nath said such analyses might take a month or two. A spokeswoman for AstraZeneca declined to comment on when the US trial would start again, saying the company "will continue to work with health authorities across the world, including the FDA, and be guided as to when other clinical trials can resume."
When the hold became public on September 8, AstraZeneca called the move "a routine action" that takes place when there is a potentially unexplained illness in one of the trials, and suggested the adverse event may not even be related to the vaccine, but it provided few other details. Some investors on a private conference call  with CEO Pascal Soriot later disclosed that the UK trial participant was a woman who experienced neurological symptoms consistent with transverse myelitis, and that she was improving. According to the investors, Soriot also revealed during the call that the trial had already been halted once before in July after a participant experienced neurological symptoms, but investigators discovered that the person had multiple sclerosis that was unrelated to the vaccination.
Some scientists and public health experts worry  that drugmakers have been rather quiet when it comes to sharing safety details about their experimental COVID-19 vaccines, and they are calling on them to be more open about how they run their trials.