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Objective: To evaluate the association between serious acute neurological illness and receipt of whole-cell pertussis vaccine, given as diphtheria-tetanus-pertussis (DTP) vaccine., Design: Population-based case-control study., Setting: Outpatient and inpatient hospital settings, physician practices, and the general population in Washington and Oregon states., Subjects: A total of 424 confirmed cases of neurological illness were identified prospectively during a 12-month period by statewide active surveillance from the population of 218,000 children 1 to 24 months of age living in Washington and Oregon (estimated 368,000 DTP immunizations given). Each case child was matched to two population control children by birth date (+/- 5 days), gender, and county of birth. Written immunization records were used to determine whether illness occurred within 7 days of immunization in case children, or within 7 days of the same reference date in control children, thus qualifying as exposed., Main Outcome Measures: Outpatient and inpatient cases of complex febrile seizures, seizures without fever, infantile spasms, and acute encephalitis/encephalopathy confirmed by an expert panel masked to immunization history., Results: The estimated odds ratio (OR) for onset of serious acute neurological illness within 7 days for young children exposed to DTP vaccine was 1.1 (95% confidence interval [CI], 0.6 to 2.0). When the analysis was restricted to children with encephalopathy or complicated seizures and adjusted for factors possibly affecting vaccine administration, the OR was 3.6 (95% CI, 0.8 to 15.2). Odds ratios for specific study diagnoses varied, but all CIs included 1. No elevated risk was observed for the largest group of illnesses studied, nonfebrile seizures (OR, 0.5; 95% CI, 0.2 to 1.5)., Conclusions: This study did not find any statistically significant increased risk of onset of serious acute neurological illness in the 7 days after DTP vaccine exposure for young children.

Objective: To evaluate the efficacy of currently used whole-cell pertussis vaccines., Design: Active surveillance to detect pertussis cases in Baltimore, Md, Denver, Colo, and Milwaukee, Wis, and investigation of secondary attack rates in 347 household contacts, aged 1 through 4 years, to estimate vaccine efficacy., Outcome Measure: Vaccine efficacy was estimated using different case definitions for pertussis., Results: Vaccine efficacy was 64%, 81%, and 95% for case definitions of mild cough, paroxysmal cough, and severe clinical illness, respectively. Requiring laboratory confirmation increased efficacy to 95% to 98% for culture-positive children and to 77% to 95% for culture- or serology-confirmed cases, depending on disease severity. Vaccine efficacy for typical paroxysmal cough increased from 44% for one diphtheria, tetanus, and pertussis vaccine dose to 80% for four or more doses., Conclusions: The trend toward increasing vaccine efficacy with different case definitions may be due to improved efficacy in preventing severe illness and to case definitions that are more specific for pertussis. Whole-cell pertussis vaccine was highly effective in preventing pertussis in preschool children exposed to infection within their households. Direct side-by-side efficacy studies of whole-cell vaccine and the recently licensed acellular vaccine will be necessary to assure that comparable protection is afforded by the new vaccines if they are to be used for immunization of infants.

From 1973 through 1984, there were 138 cases of paralytic poliomyelitis reported in the United States; 105 (76%) were vaccine associated. Of the 105 vaccine-associated cases, 35 occurred in recipients of oral polio vaccine (OPV), 50 in contacts to OPV recipients, 14 in immune deficient individuals, and six in individuals who had no history of receiving OPV or contact with recent OPV recipients. Thirty-three (94%) of the recipient cases, 41 (82%) of the contact cases, and five (36%) of the immune deficient cases were associated with the first dose of OPV. The overall frequency of vaccine-associated poliomyelitis was one case per 2.6 million doses distributed. However, the relative frequency of paralysis associated with the first dose in the OPV series was one case per 520,000 doses vs one case per 12.3 million subsequent doses. Vaccine-associated paralytic poliomyelitis is rare and the risks of OPV are small. The greatest likelihood of paralysis occurs in association with the first dose of OPV and that likelihood is reduced in subsequent doses more for recipients than for their contacts.

The morbidity and mortality associated with the 1980 heat wave in St Louis and Kansas City, Mo, were assessed retrospectively. Heat-related illness and deaths were identified by review of death certificates and hospital, emergency room, and medical examiners' records in the two cities. Data from the July 1980 heat wave were compared with data from July 1978 and 1979, when there were no heat waves. Deaths from all causes in July 1980 increased by 57% and 64% in St Louis and Kansas City, respectively, but only 10% in the predominantly rural areas of Missouri. About one of every 1,000 residents of the two cities was hospitalized for or died of heat-related illness. Incidence rates (per 100,000) of heatstroke, defined as severe heat illness with documented hyperthermia, were 26.5 and 17.6 for St Louis and Kansas City, respectively. No heatstroke cases occurred in July 1979. Heatstroke rates were ten to 12 times higher for persons aged 65 years or older than for those younger than 65 years. The ratios of age-adjusted heatstroke rates were approximately 3:1 for nonwhite v white persons and about 6:1 for low v high socioeconomic status. Public health preventive measures in future heat waves should be directed toward the urban poor, the elderly, and persons of other-than-white races.

From Jan 1 to Dec 31, 1983, 351 cases of pertussis were reported in Oklahoma. Overall, 59% of the cases were among children 3 months to 6 years of age, the target age group for pertussis vaccination; only 42% of the patients in this age group were appropriately immunized for age with diphtheria and tetanus toxoids and pertussis vaccine (DTP). A survey of 185 households in the neighborhoods of three cases found that only 65% of 57 children 3 months to 6 years of age were appropriately immunized for their age. Aggressive control of the outbreak was attempted in Oklahoma County with recommendations for widespread vaccination against pertussis. However, the effort failed to immunize 82% of the 931 children in the initial target group. Nonetheless, analysis of the reported cases suggested that less than one fourth of the cases were potentially preventable by a single additional dose of DTP, ie, in individuals 3 months to 6 years of age with a history of at least one prior dose of DTP who were not appropriately immunized for age. The optimal solution to outbreak control is outbreak prevention by ensuring that the maximal number of children younger than 7 years of age receive routine age-appropriate DTP vaccination.

The occurrence of adverse events temporally associated with diphtheria and tetanus toxoids and pertussis vaccine (DTP) has led to consideration of a delay in the schedule of initial vaccination. We developed an inferential model estimating the changes in pertussis- and DTP-associated health outcomes that might occur if initial DTP administration were delayed from 2, 4, and 6 months to 8, 10, and 12 months of age. An additional 636 cases of pertussis--115 of which would be associated with complications, including two encephalopathies--were projected to occur under the proposed as compared to the current schedule. Adverse medical events attributable to the vaccine were assumed to remain unchanged following the change in schedule. We projected 353 fewer chance associations with sudden infant death syndrome but 1311 more chance associations between DTP and seizures. These estimates suggest that the current schedule of vaccinating infants at 2, 4, and 6 months of age is casually associated with less morbidity and should be continued.