Estimates of pertussis vaccine effectiveness in United States air force pediatric dependents.

BACKGROUND

Pertussis vaccination compliance is critical for reduction in the prevalence of disease; however, the current acellular pertussis vaccine may not provide sufficient protection from infection. This study examined acellular pertussis vaccine effectiveness (VE) for Air Force dependents less than 12 years of age.

METHODS

We conducted a case-control study among Air Force pediatric dependents from 2011 to 2013, comparing cases with positive pertussis test results to controls who received the same lab tests with a negative result. Our study population was categorized by age group and vaccination status based on the Centers for Disease Control and Prevention recommended pertussis vaccination schedule. VE was calculated with respect to vaccination status and pertussis lab results.

RESULTS

We compared 27 pertussis laboratory positive cases with 974 pertussis laboratory negative controls, 2 months to <12 years old. Comparing completely vaccinated to non-vaccinated patients, the overall VE was 78.3% (95% confidence interval (CI): 48.6, 90.8; p<0.001). VE was highest among those 15 months to <6 years old: 97.6% (95% CI: 78.5, 99.7; p<0.001). Children 6 to <12 years old had the lowest VE: 48.5% (95% CI: -74.0, 84.7; p=0.28). Comparing partially vaccinated patients to nonvaccinated patients yielded 64.2% (95% CI: -7.2, 88.1; p=0.06) overall VE.

CONCLUSIONS

Acellular pertussis vaccination was effective at preventing laboratory confirmed pertussis among our Air Force pediatric dependent population, with highest protection among completely vaccinated, young children. Older children received the lowest amount of protection. Partial vaccination had near significant protection. Our overall calculated pertussis VE corroborates other pertussis VE studies looking at similar age groups.