- Researchers running two large studies of experimental coronavirus vaccines from AstraZeneca and Johnson & Johnson will be allowed to resume vaccinating volunteers, the companies said Friday, after safety reviews cleared both to restart.
- In each case, the trials were paused after a participant sickened with an unexplained illness, raising concerns of potentially serious adverse reaction. The halt to J&J's study was more recent, occurring last week, while AstraZeneca's trial was stopped in early September.
- A trial monitoring board for J&J's study found no evidence the company's vaccine was the cause, J&J said in a statement, while an investigation by the Food and Drug Administration was not able to link AstraZeneca's shot to the illness observed early last month, The Wall Street Journal reported.
Trial pauses aren't out of the ordinary in clinical testing, particularly for large studies involving thousands of volunteers, like those being run by AstraZeneca and J&J. With so many participants, some are bound to get sick with ailments unrelated to vaccination. Disentangling those health problems from potential adverse reactions to an experimental shot can be difficult and time-consuming.
Experts generally viewed the halts to AstraZeneca's and J&J's testing as prudent, and a sign the companies were taking safety seriously despite the headlong rush to get a vaccine for SARS-CoV-2 over the finish line.
AstraZeneca and its partner, the University of Oxford, paused studies of their vaccine worldwide in early September after a participant in a U.K. study became ill. Neither the company nor the university ever confirmed the diagnosis, but the participant's symptoms were reportedly consistent with a rare neurological condition that can be caused by viral infections.
While studies of the vaccine quickly resumed in the U.K., Japan, Brazil and South Africa, the trial halt dragged on in the U.S. for an unusually long time, spurring concerns of a deeper issue with the shot.
Those worries grew when J&J in mid-October announced it was pausing trials of its experimental shot after an unexplained illness in one study volunteer. J&J's candidate is different than AstraZeneca's, but they use a similar type of modified virus to train the body's immune system against SARS-Cov-2.
In its statement Friday, J&J said the independent data safety and monitoring board overseeing its study had recommended restarting trial recruitment. After consulting with the FDA, the drugmaker is now working to resume the trial in the U.S., which is planned to enroll 60,000 volunteers across eight countries.
"After a thorough evaluation of a serious medical event experienced by one study participant, no clear cause has been identified," J&J said.
Discussions with other regulators to continue study of the vaccine elsewhere are "progressing," the drugmaker added.
Although AstraZeneca acted voluntarily to pause studies of its vaccine back in September, the trial halt eventually involved the FDA directly, and the regulator reportedly conducted its own investigation.
According to The Wall Street Journal, the FDA did not find the vaccine to be linked to the participant's adverse reaction, or to an earlier unexplained illness in another volunteer. The agency could not rule out a connection, however.
Neither the FDA nor AstraZeneca returned BioPharma Dive's request for comment.
With a green light from the agency, AstraZeneca can now continue recruiting volunteers into its large U.S. study, which is expected to enroll some 30,000 participants. Globally, some 20,000 people have been recruited into AstraZeneca and Oxford's other studies.
Both J&J's and AstraZeneca's vaccines are among the furthest along in testing. Early trials of each showed the shots were capable of spurring an immune response against the coronavirus — an encouraging sign, but not yet proof they can protect against infection or disease. The large, late-stage studies now ongoing are meant to determine that conclusively.
Side effects for both shots were mostly mild to moderate in nature, typically involving headaches, chills and fatigue that, in the case of AstraZeneca's early study, were treatable with Aspirin.
AstraZeneca expects to report data from its late-stage tests later this year, which, if positive, could support an emergency clearance.
J&J hasn't said when results from its trial could come, but plans to have the first batches of its vaccine ready for distribution by early 2021, assuming positive results and approval from regulators.
Unlike other vaccines in late-stage testing, J&J's is given as one shot rather than two, a potential advantage in governments' plans to inoculate tens or hundreds of millions of their citizens.
Editor's note: This article has been updated throughout to include Johnson & Johnson's announcement of preparations to resume its coronavirus vaccine study.