Local scientists say pause of COVID-19 vaccine trial including UCSD isn’t necessarily cause for concern

British pharmaceutical giant AstraZeneca
British pharmaceutical giant AstraZeneca paused its COVID-19 vaccine trial after a person given the vaccine showed symptoms of spinal inflammation.
(Getty Images)

British pharma giant AstraZeneca halted its trial to investigate whether its vaccine caused a participant’s illness.


From San Diego to South Africa, AstraZeneca’s COVID-19 vaccine trial paused Tuesday after a person given the vaccine showed symptoms of spinal inflammation.

On rare occasions, previous vaccines have triggered similar symptoms in a small percentage of people. But local scientists emphasized that it’s still unclear whether AstraZeneca’s vaccine even caused the symptoms and said this level of caution from the British pharma giant is a good sign.

“It’s reassuring that the trials are being carried out according to the rules,” said Dennis Burton, an immunologist at Scripps Research in La Jolla. “Any vaccine that comes forward has to be safe.”

AstraZeneca stopped its trial after a woman given the vaccine in the United Kingdom became ill, according to initial reports from STAT, a national health publication. According to the reports, her symptoms, which are improving, match a form of spinal inflammation known as transverse myelitis, though there has been no official diagnosis.

The company previously paused its trial in July after a participant showed symptoms of what turned out to be multiple sclerosis. An independent panel concluded that the disease was coincidental and not caused by the vaccine.

It’s possible that the same will be true in this case, said Dr. Gary Firestein, director of UC San Diego’s Clinical and Translational Research Institute.

“In a study involving tens of thousands of people, a certain percentage of those individuals will have something that happens medically that would have happened regardless of participation in the clinical trial,” Firestein said.

“That being said, it’s critical to take these types of events very seriously.”

Vaccine trial pauses are common, according to Firestein. It’s just that most trials aren’t so closely tracked by the public and media.

During the pause, a panel of researchers not affiliated with AstraZeneca will determine whether the participant’s symptoms were triggered by the vaccine. It’s unclear how long the hiatus will last.

The company’s U.S. trial sites include UCSD, which plans to enroll 1,600 in San Diego and 1,200 at a satellite site at El Centro Regional Medical Center in Imperial County. Naval Medical Center San Diego is one of five military medical facilities participating. But none of the local sites had begun before the halt.

UC San Diego will enroll a large, diverse group of area residents in a trial of a COVID-19 vaccine developed by researchers at Oxford University and British pharma giant AstraZeneca set to begin Tuesday, Sept. 8.

In the past, some vaccines have sparked immune responses that target the spinal cord, said Dr. Revere Kinkel of UCSD, who specializes in the interactions between the immune and nervous systems. Such cases of immune friendly fire can lead to numbness and difficulty moving limbs below the damaged area.

“It’s a real rare thing to have happen with vaccines, but it’s described with almost all vaccines,” Kinkel said. “It’s been described with hepatitis vaccine, measles vaccines, all the childhood vaccines.”

If the symptoms are a real side effect of AstraZeneca’s COVID-19 vaccine, it will be important to understand how common they are, Kinkel said. In one analysis, researchers identified 37 cases of transverse myelitis reported after vaccination between 1970 and 2009. That includes 13 people who received the Hepatitis B vaccine, which is widely administered, 90 percent effective and generally regarded as safe.

Regardless of the independent panel’s conclusions, the trial’s pause may further weaken already tepid support for a COVID-19 vaccine. According to an August Gallup Poll, about one in three Americans surveyed said they would not get a free COVID-19 vaccine that was approved by the U.S. Food and Drug Administration.

That means it’s going to be more important than ever to listen and answer the public’s questions about the ongoing trials, said Dr. Christian Ramers of Family Health Centers of San Diego.

“In terms of engaging the community, this makes that type of work even more important,” Ramers said. ◆