Several large clinical trials for AstraZeneca’s COVID-19 vaccine have been halted due to a possible serious adverse reaction. The company is now investigating whether or not the issue is directly related to the vaccine.
AstraZeneca’s COVID-19 vaccine, which is being developed with researchers at Oxford University, is one of just a few candidates that’s in Phase 3 trials in the U.S. right now, meaning it is one of those furthest along in the testing process. Previously, the vaccine had been in testing in combined Phase 2 and 3 trials in the U.K. and Brazil as well as a combined Phase 1 and 2 trial in South Africa. But after a trial participant in the U.K. developed a health issue that may be a serious adverse reaction to the vaccine, the company halted its U.S. trial, STAT reported earlier this week.
And according to a press release from the company, all of the trials for this vaccine have now been put on pause for the time being. “As part of the ongoing randomized, controlled clinical trials of the AstraZeneca Oxford coronavirus vaccine, a standard review process has been triggered,” according to the company’s press release. That review process has led “to the voluntary pause of vaccination across all trials to allow an independent committee to review the safety data of a single event of an unexplained illness that occurred in the U.K. Phase 3 trial.”
There aren’t a ton of public details about the participant’s condition or the timing of their diagnosis, but the New York Times reports that the participant was recently diagnosed with transverse myelitis. This is a neurological condition in which the spinal cord becomes inflamed. The inflammation then damages the myelin that covers and protects the nerve fibers, the Mayo Clinic explains, which can cause sharp pain in the lower back, weakness in the limbs, odd sensations of numbness or tingling, and bowel or bladder issues. Experts don’t fully understand what causes transverse myelitis, but it can be triggered by some viral and bacterial illnesses, such as Epstein-Barr virus and West Nile virus.
It’s obviously not good that someone in the trial may have developed a serious health condition, but whether or not the condition is related to the vaccine, the fact that the company is halting the trial to get more information is a good sign. This is the way trials are supposed to work in order to ensure the vaccine is safe before it reaches the general public. In fact, AstraZeneca is one of nine pharmaceutical companies that just signed a pledge to not prioritize speed over safety when developing a coronavirus vaccine, SELF reported previously.
As much as we want a vaccine, what we really want is a vaccine that has been proven both safe and effective in extensive clinical trials. That may take some extra time as researchers and pharmaceutical companies work through issues like these, but it’s better to do that than, well, not.