‘Vaccine-derived outbreak’ is a brand new term for 2020. What in the name of the unholy Boston Red Sox is a vaccine-derived outbreak?
Not new at all. The Cutter Incident from 1955 was hardly the first or the only case of bad quality control or bad judgement resulting in people getting sick who didn’t need to. In that case, a mom ‘n pop laboratory making the polio vaccine screwed up and people got sick with polio as a result.