The trial was put on hold because there is a volunteer in the study who potentially had a serious adverse reaction to the vaccine. When that happens, the trial must be paused so the researchers can understand what happened, and whether any action is needed. As STAT reports today, the trial participant is a woman in the United Kingdom who experienced neurological symptoms “consistent with a rare but serious spinal inflammatory disorder called transverse myelitis.” The woman’s diagnosis is not yet confirmed, but she seems to be recovering and is expected to be discharged from the hospital today. As STAT reports, this appears to be the first phase 3 Covid-19 vaccine trial to be put on hold, but “such holds are not uncommon, and it’s not clear yet how long AstraZeneca’s will last.”
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