AstraZeneca's final-stage clinical trial for its COVID-19 vaccine has been delayed in the U.S. for over a month, and there's no public information on when it will resume.
A timeline of events since the trial was halted:
Sept. 9: AstraZeneca announces that it has taken a "voluntary pause" of its phase 3 trial after an adverse reaction in a patient in the U.K.
Sept. 10: During a conference call with investors, AstraZeneca CEO Pascal Soriot discloses that the vaccine trial had also been halted in July after a participant had neurological symptoms, later attributed to multiple sclerosis and not the vaccine. Some experts began criticizing the drugmaker for a lack of transparency.
Sept. 11: Mr. Soriot says the company should know by the end of the year whether its vaccine is safe and effective.
Sept. 12: AstraZeneca resumes its trial in the U.K. after gaining approval from the Medicines Health Regulatory Authority.
Sept. 15: An official from the National Institutes of Health tells Kaiser Health News that the agency is "very concerned" about the delayed AstraZeneca's trial.
Sept. 18: A safety report shows that the U.K. woman who had the adverse reaction that halted the trial had suffered from transverse myelitis, a rare neurological condition in which the spinal cord becomes inflamed. It's still not known if the transverse myelitis is related to AstraZeneca's vaccine.
Oct. 1: The FDA says it is widening its investigation of the vaccine by examining the results of earlier studies of other vaccines made by AstraZeneca scientists to see if similar side effects emerged in those trials.
Oct. 21: A participant in the Brazil arm of the study dies, but the drugmaker announces that the participant received a placebo, not the vaccine. The cause of the study participant's death is not revealed.