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The United States has achieved over 97% immunization of children by school age and has reduced the incidence of vaccine-preventable diseases by more than 90% since the prevaccination era. However, children often do not receive immunizations at the recommended age, and in densely populated urban areas this delay in immunization has led to epidemics of measles. Correctable deficiencies of the immunization delivery system have been identified in these areas. To respond to needs, the public health infrastructure must be strengthened, and active participation from the private sector must be obtained, both in delivery of immunizations and in assessment of performance. Appropriate action must be stimulated by the provision of timely information on immunization coverage and on indicators of program performance at the local level.

A comparative field trial of three rubella virus vaccines (Cendehill, HPV-77 DE-5, and HPV-77 DK-12) was initiated in 1969 on the islands of Kauai and Hawaii in the state of Hawaii. In 1985, follow-up was reinitiated to assess the long-term durability of vaccine-induced immunity. Enzyme-linked immunosorbent assays of serum specimens from 1290 participants demonstrated seropositive rates of 92.4% and 96.4% at screening levels of 10 (protective level) and 7 (lowest detectable level) IU/mL, respectively. The seropositive rates were not related to reinfection or reimmunizations. These findings indicate that vaccine-induced rubella antibodies are detectable in almost all persons up to 16 years after successful vaccination.

Since the introduction of acellular pertussis vaccines in Japan late in 1981, more than 20 million doses have been administered, mostly to children 2 years of age and older. Clinical studies indicate that mild local and febrile reactions are less frequent after administration of acellular pertussis vaccines than after whole-cell vaccines. Serious adverse events with sequelae occurred in 2-year-old children at approximately the same low rate during the period 1975 through August 1981, when whole-cell vaccines were used, and during August 1981 through 1984, when acellular vaccines were used exclusively. Five household contact studies have yielded vaccine efficacy estimates ranging from 78% to 92% in children 1 year of age or older. In addition, there has been a continuing decrease in reported pertussis incidence from the epidemic peak in 1979. Additional data on the safety and efficacy of acellular pertussis vaccines administered to infants would be useful in consideration of acellular pertussis vaccine licensure in the United States.