Oxford hired an outside manufacturer to produce large quantities of the vaccine for the trial. But when researchers received a sample of the vaccine and measured its strength, they noticed something strange. Using a different measurement technique than the manufacturer, Oxford found the concentration of viral particles in the vaccine to be double the level that the manufacturer had found.Oxford researchers didn’t know which measurement to trust. They decided to use a lower-strength dose. That way, even if their measurement was wrong, the dosage was sure to be safe, albeit smaller than originally intended.Participants would get two …
