In Reply.—The analysis proposed by Drs Welch and Beekman makes several assumptions as follows:
They assume that the children are deficient only in mumps vaccine. It must be recalled that children's immunization status is being assessed generally, not just for mumps, and that children who are deficient in mumps vaccine may well also be deficient in other vaccines. Although exact data are not available, the theoretical cohort of 1 million children needing mumps vaccine may also include, for example, 500,000 children who need measles vaccine or 300,000 who need rubella vaccine.
They assume that all of the vaccine administered would be administered in physicians' offices, whereas it is likely that a significant proportion would be administered through public clinics at a lower cost per immunization.
They assume a half day of school absence for each child who needs mumps immunization. Experience in most states has