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Clin Infect Dis. 2019 Mar 16. pii: ciz217. doi: 10.1093/cid/ciz217. [Epub ahead of print]

Maternal Vaccination in Argentina: Tdap Vaccine Effectiveness During Pregnancy in Preventing Pertussis in Infants Less Than 2 Months of Age.

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Dirección de Control de Enfermedades Inmunoprevenibles, Ministerio de Salud de la Nación, Buenos Aires, Argentina (VR affiliated: 2011-2016; MdVJ affiliated 2011-present; SS affiliated: 2007-2015; CV affiliated: 2007-2016).
Meningitis and Vaccine Preventable Diseases Branch, Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
Hospital del Niño Jesús, Tucumán, Argentina.
Hospital Público Materno Infantil, Salta, Argentina.
Hospital "P. de Elizalde", Buenos Aires, Argentina.
Hospital de Niños "R. Gutiérrez", Buenos Aires, Argentina.
Hospital "Dr. H. Heller", Neuquén, Argentina.



In 2011, Argentina experienced the highest pertussis incidence and mortality rates in the last decade; 60% of deaths were among infants aged <2 months. In response, a dose of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine was recommended for all pregnant women at ≥20 weeks of gestation. Although recent studies suggest maternal Tdap vaccination is effective at preventing infant disease, no data have come from low or middle-income countries, nor from ones using whole-cell pertussis vaccines for primary immunization.


We conducted a matched case-control evaluation to assess the effectiveness of maternal Tdap vaccination in preventing pertussis among infants aged <2 months in Argentina. Pertussis case-patients identified from September 2012 to March 2016 at six hospital sites and confirmed by polymerase chain reaction testing were included. Five randomly selected controls were matched to each case-patient by hospital site and mother's health district. We used multivariable conditional logistic regression to calculate odds ratios (ORs). Vaccine effectiveness (VE) was estimated as (1 - OR) × 100%.


Seventy-one case-patients and 300 controls were included in the analysis. Forty-nine percent of case-patients and 78% of controls had mothers who were vaccinated during pregnancy. Overall Tdap VE was estimated at 80.7% (95% confidence intervals: 52.1%-92.2%). We found similar VE whether Tdap was administered during the second or third trimester.


Tdap vaccination during pregnancy is effective in preventing pertussis in infants aged <2 months in Argentina, with similar effectiveness whether administered during the second or third trimester of pregnancy.


Tdap; infant pertussis; maternal immunization; pregnancy; vaccine effectiveness


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