First Pertussis Vaccine Dose and Prevention of Infant Mortality

BACKGROUND: American infants are at highest risk of severe pertussis and death. We investigated the role of ≥1 pertussis vaccinations in preventing pertussis-related deaths and risk markers for death among infants aged <42 days.

METHODS: We analyzed characteristics of fatal and nonfatal infant pertussis cases reported nationally during 1991–2008. Infants were categorized into 2 age groups on the basis of eligibility to receive a first pertussis vaccine dose at age 6 weeks; dose 1 was considered valid if given ≥14 days before illness onset. Multivariable logistic regression was used to estimate the effect of ≥1 pertussis vaccine doses on outcome and risk markers.

RESULTS: Pertussis-related deaths occurred among 258 of 45 404 cases. Fatal and nonfatal cases were confirmed by culture (54% vs 49%) and polymerase chain reaction (31% vs 27%). All deaths occurred before age 34 weeks at illness onset; 64% occurred before age 6 weeks. Among infants aged ≥42 days, receiving ≥1 doses of vaccine protected against death (adjusted odds ratio [aOR]: 0.28; 95% confidence interval [CI]: 0.11–0.74), hospitalization (aOR: 0.69; 95% CI: 0.63–0.77), and pneumonia (aOR: 0.80; 95% CI: 0.68–0.95). Risk was elevated for Hispanic ethnicity (aOR: 2.28; 95% CI: 1.36–3.83) and American Indian/Alaska Native race (aOR: 5.15; 95% CI: 2.37–11.2) and lower for recommended antibiotic treatment (aOR: 0.28; 95% CI: 0.16–0.47). Among infants aged <42 days, risk was elevated for Hispanic ethnicity and lower with recommended antibiotic use.

CONCLUSIONS: The first pertussis vaccine dose and antibiotic treatment protect against death, hospitalization, and pneumonia.