title: Impact of a maternal immunization program against pertussis in a developing country.
abstract: Pertussis disease is a growing concern for developing countries. In Argentina, rates of illness and death peaked in 2011. More than 50% of fatalities due to pertussis occurred in infants younger than two months of age, too young for vaccination. In 2012, the government offered immunization with a vaccine containing Tdap to all pregnant women after 20weeks of gestation with the intent of reducing morbidity and mortality in young infants.
  
  
  
  Maternal acellular pertussis vaccine impact on reducing infant disease burden was estimated based on data from the Argentinean Health Surveillance System. We divided Argentinean states in two groups experiencing high (>50) and low (⩽50) Tdap vaccine coverage and compared these two groups using a Bayesian structural time-series model. Low coverage regions were used as a control group, and the time series were compared before and after the implementation of the Tdap program.
  
  
  
  We observed a relative reduction of 51% (95% CI [-67%, -35%]; p=0.001) in pertussis cases in high coverage states in comparison with the low coverage areas. Analysis of infants between two and six months showed a 44% (95% CI [-66%, -24%]; p=0.001) reduction in illness. Number of deaths was highest in 2011 with 76 fatalities, for an incidence rate of 2.9 per 100,000. Comparing with 2011, rates decreased by 87% to 10 subjects, or 0.9 per 100,000 in 2013.
  
  
  
  We show an age-dependent protective effect of maternal Tdap immunization in a developing country for infants younger than six months.
authors.affiliation: Dirección Nacional de Control de Enfermedades Inmunoprevenibles (DiNaCEI), Ministerio de Salud de la Nación, Argentina. Electronic address: cvizzotti@dicei.msal.gov.ar.
authors.forename: Carla
authors.initials: C
authors.lastname: Vizzotti
authors.affiliation: Dirección Nacional de Control de Enfermedades Inmunoprevenibles (DiNaCEI), Ministerio de Salud de la Nación, Argentina.
authors.forename: Maria V
authors.initials: MV
authors.lastname: Juarez
authors.affiliation: Fundacion INFANT, Buenos Aires, Argentina.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Bergel
authors.affiliation: Dirección Nacional de Control de Enfermedades Inmunoprevenibles (DiNaCEI), Ministerio de Salud de la Nación, Argentina.
authors.forename: Viviana
authors.initials: V
authors.lastname: Romanin
authors.affiliation: Dirección Nacional de Control de Enfermedades Inmunoprevenibles (DiNaCEI), Ministerio de Salud de la Nación, Argentina.
authors.forename: Gloria
authors.initials: G
authors.lastname: Califano
authors.affiliation: Dirección Nacional de Control de Enfermedades Inmunoprevenibles (DiNaCEI), Ministerio de Salud de la Nación, Argentina.
authors.forename: Sandra
authors.initials: S
authors.lastname: Sagradini
authors.affiliation: Dirección Nacional de Control de Enfermedades Inmunoprevenibles (DiNaCEI), Ministerio de Salud de la Nación, Argentina.
authors.forename: Carolina
authors.initials: C
authors.lastname: Rancaño
authors.affiliation: Dirección Nacional de Control de Enfermedades Inmunoprevenibles (DiNaCEI), Ministerio de Salud de la Nación, Argentina.
authors.forename: Analía
authors.initials: A
authors.lastname: Aquino
authors.affiliation: Fundacion INFANT, Buenos Aires, Argentina; Vanderbilt University, Nashville, TN, United States; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.
authors.forename: Romina
authors.initials: R
authors.lastname: Libster
authors.affiliation: Fundacion INFANT, Buenos Aires, Argentina; Vanderbilt University, Nashville, TN, United States.
authors.forename: Fernando P
authors.initials: FP
authors.lastname: Polack
authors.affiliation: Dirección Nacional de Control de Enfermedades Inmunoprevenibles (DiNaCEI), Ministerio de Salud de la Nación, Argentina.
authors.forename: Juan
authors.initials: J
authors.lastname: Manzur
mesh_terms: D001118:Argentina / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003906:Developing Countries; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines / Q000008:administration & dosage*; D018562:Disease Transmission, Infectious / Q000517:prevention & control*; D005260:Female; D006801:Humans; D017589:Immunization Programs; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D037841:Pregnant People; D014611:Vaccination / Q000706:statistics & numerical data*; D014917:Whooping Cough / Q000453:epidemiology* / Q000517:prevention & control*
chemical_list: D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines
keywords: Maternal immunization; Pertussis; Vaccine