Successful immunization of infants with and without maternal antibody by aerosolized measles vaccine. II. Vaccine comparisons and evidence for multiple antibody response
A. B. Sabin, A. Flores Arechiga, J. Fernandez de Castro, P. Albrecht, J. L. Sever and I. Shekarchi
In 4- and 5-month-old infants in whom the undiluted chick embryo fibroblast
(CEF) Schwarz strain measles vaccine had a poor immunogenic effect, there
was an increase in immunogenicity when the high sugar concentration was
diminished without reference to added albumin. The human diploid cell (HDC)
measles vaccine was still superior in this age group even in a lower
concentration of the Ikic, Edmonston-Zagreb strain of virus. More
aerosolized, HDC Ikic strain virus was required for high seroconversion
rates in 4- and 5-month-old infants who had higher titers of prevaccination
plaque-neutralizing (PN) antibodies. Some of these infants had a delayed
immune response that was absent at six weeks but present at three months
after vaccination. The data provided evidence that the PN and enzyme-linked
immunosorbent assay techniques measured different antibodies that develop
and persist in different ways in 4- to 5-month-old infants. The HDC
lyophilized measles vaccine yielded unexpectedly high seroconversion rates
after subcutaneous injection of 5,000 plaque-forming units (PFUs) in 4-,
5-, and 6-month-old infants: 69%, 89%, and 100% respectively, at 14 weeks.
In 12- to 23-month-old infants there was seroconversion of 92% and 100% at
six weeks after inhalation of an estimated 175 PFUs of the CEF vaccine and
375 PFUs of the HDC vaccine, respectively. Within six weeks after
vaccination, the PN antibody titers were significantly higher with the CEF
vaccine (geometric mean titer of 2,275) than with the HDC vaccine
(geometric mean titer of 343).
