M A J O R A R T I C L E
Impact of Maternal Postpartum Tetanus and
Diphtheria Toxoids and Acellular Pertussis
Immunization on Infant Pertussis Infection
Luis A. Castagnini,1C. Mary Healy,1,3Marcia A. Rench,1Susan H. Wootton,4Flor M. Munoz,1,2and Carol J. Baker1,2,3
1Department of Pediatrics and2Department Molecular Virology and Microbiology, Baylor College of Medicine;3Center for Vaccine Awareness and
Research, Texas Children's Hospital; and4Department of Pediatrics, University of Texas Health Science Center at Houston
(See the Editorial Commentary by Libster and Edwards, on pages 85–7.)
and Prevention recommend tetanus and diphtheria toxoids and acellular pertussis (Tdap) vaccine for postpartum
women before hospital discharge. In January 2008, this recommendation was implemented in a predominantly
Hispanic, medically underserved population at Ben Taub General Hospital (BTGH) in Houston (hereafter the
Methods.A cross-sectional study compared preintervention (July 2000 through December 2007) and
postintervention (January 2008 through May 2009) periods. Pertussis diagnosis was determined using International
Classification of Diseases, Ninth Revision (ICD-9) codes and microbiology reports from 4 major children’s hospitals
in Houston. Only those infants #6 months of age with laboratory-confirmed pertussis illness were included. The
proportions of pertussis-infected infants born at BTGH in the pre- and postintervention periods were compared.
Results.Of 514 infants with pertussis, 378 (73.5%) were identified during preintervention and 136 (26.5%)
during postintervention years. These groups were similar in age (mean, 79.3 vs 72 days; P 5 .08), sex (males, 55% vs
52%; P 5 .48), length of hospitalization (mean, 9.7 vs 10.7 days; P 5 .62), mortality (2 deaths each; P 5 .29) and
hospital of pertussis diagnosis. After adjustment for age, sex, and ethnicity, the proportions of pertussis-infected
infants born at BTGH and potentially protected through maternal postpartum Tdap immunization were similar for
the 2 periods (6.9% vs 8.8%; odds ratio, 1.06; 95% confidence interval, 0.5–2.2; P 5 .87).
Conclusions.Immunizing only postpartum mothers with Tdap vaccine did not reduce pertussis illness in
infants #6 months of age. Efforts should be directed at immunizing all household and key contacts of newborns
with Tdap, not just mothers.
Mothers often are the source of pertussis illness in young infants. The Centers for Disease Control
Despite high infant immunizations rates, pertussis is the
only vaccine-preventable disease in the United States for
which the incidence reached a nadir in the late 1970s,
subsequently increased, and remains high. Although the
greatest number of pertussis cases reported to the
Centers for Disease Control and Prevention (CDC)
annually occur in adolescents and young adults, the
highest age-specific attack rate is among infants aged
,6 months, in whom rates are up to 20-fold higher than
in other age groups [1, 2]. The highest rate of pertussis-
associated complications, hospitalizations, and deaths
also occursin young infants who have not yet completed
their 3-dose pertussis immunization series at 6 months of
age [2–6]. For reasons that are poorly understood, His-
panic infants have substantially higher rates of pertussis-
associated complications and death than infants of
other ethnicities [2, 5]. The 2010 pertussis epidemic in
California, which afflicted more persons than in the
previous 65 years, powerfully illustrates the vulnera-
bility of young infants and the disparity in pertussis
rates for Hispanic infants .
Received 30 March 2011; accepted 17 August 2011; electronically published 10
Correspondence: Carol J. Baker, MD, Department of Pediatrics, Baylor College
of Medicine, 1102 Bates St, Ste 1120, Houston, TX 77030 (email@example.com).
Clinical Infectious Diseases
? The Author 2011. Published by Oxford University Press on behalf of the Infectious
Diseases Society of America. All rights reserved. For Permissions, please e-mail:
d CID 2012:54 (1 January)
d Castagnini et al
by guest on November 17, 2015
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