Parents across the United States are anxiously awaiting the regulators’ decision, which could affect family life and the operation of schools. Clearance depends not only on the strength of the clinical trial data, but on whether they can prove to regulators that they are able to properly manufacture a new pediatric formulation…

Pfizer has proposed giving children one-third of the adult dosage. That might require adding more diluent to each injection or using a different vial or syringe. The company was expected to describe the method it intended to use in its submission to the Food and Drug Administration.

Regulators will have to examine the purity and stability of mass-manufactured doses of the vaccine and determine that it matches the quality and potency of doses given to children in clinical trials. A pediatric dose will also most likely require new labeling, with special codes that would allow the Centers for Disease Control and Prevention to track specific lots in case of reports of serious side effects.