Conference Dates

June 12 – 17, 2022


Vaccine adverse reaction investigations typically focus on the commonalities of all doses of a vaccine, such as excipients. The possibility that some adverse reactions may be caused by defective doses is difficult to investigate due to lack of data on the quality of individual doses. Here, a defective dose means its critical quality attributes are outside the acceptable range. It is unrealistic to expect zero defect rate when a vaccine is administered; defects may occur during manufacturing, which is not very precise, or during distribution, where mishandling such as cold chain breaches may happen. Manufacturing errors and product mishandling will lead to a few defective doses among many quality doses. Unless the defect rate of a vaccine at vaccination sites is known to be markedly lower than the adverse reaction rate, the possibility that some adverse reactions are caused by defective doses cannot be excluded.

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