- The U.K. drugs regulator and an independent committee have agreed to let vaccinations with AstraZeneca and the University of Oxford's experimental coronavirus shot resume at U.K.-based clinical trial sites, less than a week after testing was paused for a safety review.
- AstraZeneca and Oxford had halted study of their vaccine worldwide after a participant in a U.K. study developed an unexplained neurological illness. Following an investigation, an independent safety review committee and the U.K.'s Medicines Health Regulatory Authority concluded testing could safely restart.
- The decision in the U.K. doesn't yet mean studies will resume in other parts of the world, including in the U.S., where AstraZeneca is running its largest late-stage trial. AstraZeneca is working to get that and other ongoing studies started, but those decisions will be guided by other health authorities.
News this week of the trial volunteer's suspected adverse reaction looked to be a potentially significant setback for what has been one of the world's most advanced vaccine programs.
AstraZeneca CEO Pascal Soriot reportedly explained in an online event afterwards that the participant developed neurological symptoms characteristic of transverse myelitis, an inflammation of the spinal cord, though a diagnosis had not been officially made.
The scrutiny of AstraZeneca and Oxford's studies also drew attention to an earlier study pause that had gone unreported, when a study volunteer showed neurological symptoms later judged to be unrelated to vaccination.
Such safety reviews are typical in clinical trials and offer a way for investigators to check whether an experimental vaccine might have caused a health problem before more volunteers receive it. In this case, however, the pause was also a reminder of the importance of large-scale trials, which are needed to detect rare, potentially serious side effects that might not show up in small, early tests.
In the race to develop a coronavirus vaccine, developers are moving faster than ever before, bringing concerns such side effects might go unnoticed.
"In large trials such as this, it is expected that some participants will become unwell and every case must be carefully evaluated to ensure careful assessment of safety," Oxford said in a statement.
AstraZeneca's sparse communication about the event drew criticism, however, particularly after the drugmaker signed a pledge with eight other vaccine developers not to cut corners.
Analysts on Wall Street speculated weeks or even months would be needed to review the case before testing could resume. Transverse myelitis can be caused by viral infections and a link to AstraZeneca and Oxford's vaccine, while uncertain, was seen as plausible.
But surprisingly, the company and Oxford each put out statements Saturday saying an independent safety review committee in the U.K. had completed its investigation, and recommended to the MHRA that testing should continue. The agency agreed, allowing vaccinations to resume in the country.
Questions regarding the event will likely linger, though. Neither AstraZeneca nor Oxford provided details about the case or the conclusions of the review board. AstraZeneca said trial investigators and participants "will be updated with the relevant information," which will be disclosed on global clinical registries.
Some 18,000 people have received its vaccine so far, Oxford said in its statement. Side effects, like chills, fatigue, and fever, have been generally mild to moderate.
While testing is restarting in the U.K., it's unclear when vaccinations might resume elsewhere. Soriot said this week that if the safety review checked out, the company would be on track to have data to submit to regulators by the end of the year. That puts it slightly behind Moderna and partners BioNTech and Pfizer, which are also running large efficacy trials of their respective vaccines. Neither of those groups have reported trial stoppages.
Pfizer and BioNTech on Saturday proposed boosting the size of their Phase 3 trial to 44,000 volunteers, from a planned 30,000, to enroll a more diverse group of participants. They still expect, however, to report interim results by the end of October.