Pediatrics
June 2015, VOLUME 135 / ISSUE 6
http://pediatrics.aappublications.org/current.shtml

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Article
Tdap Vaccine Effectiveness in Adolescents During the 2012 Washington State Pertussis Epidemic
Anna M. Acosta, MDa,b, Chas DeBolt, RN, MPHc, Azadeh Tasslimi, MPHc, Melissa Lewis, MPHd, Laurie K. Stewart, MSc, Lara K. Misegades, PhD, MSb, Nancy E. Messonnier, MDb, Thomas A. Clark, MD, MPHb, Stacey W. Martin, MSb, and Manisha Patel, MD, MSb
Author Affiliations
aEpidemic Intelligence Service, Scientific Education and Professional Development Program Office,
bMeningitis and Vaccine Preventable Disease Branch, Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, and
dBiostatistics Office, Division of Bacterial Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; and
cCommunicable Disease Epidemiology, Washington State Department of Health, Shoreline, Washington
Abstract
BACKGROUND: Acellular pertussis vaccines replaced whole-cell vaccines for the 5-dose childhood vaccination series in 1997. A sixth dose of pertussis-containing vaccine, tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis, adsorbed (Tdap), was recommended in 2005 for adolescents and adults. Studies examining Tdap vaccine effectiveness (VE) among adolescents who have received all acellular vaccines are limited.
METHODS: To assess Tdap VE and duration of protection, we conducted a matched case-control study during the 2012 pertussis epidemic in Washington among adolescents born during 1993–2000. All pertussis cases reported from January 1 through June 30, 2012, in 7 counties were included; 3 controls were matched by primary provider clinic and birth year to each case. Vaccination histories were obtained through medical records, the state immunization registry, and parent interviews. Participants were classified by type of pertussis vaccine received on the basis of birth year: a mix of whole-cell and acellular vaccines (1993–1997) or all acellular vaccines (1998–2000). We used conditional logistic regression to calculate odds ratios comparing Tdap receipt between cases and controls.
RESULTS: Among adolescents who received all acellular vaccines (450 cases, 1246 controls), overall Tdap VE was 63.9% (95% confidence interval [CI]: 50% to 74%). VE within 1 year of vaccination was 73% (95% CI: 60% to 82%). At 2 to 4 years postvaccination, VE declined to 34% (95% CI: −0.03% to 58%).
CONCLUSIONS: Tdap protection wanes within 2 to 4 years. Lack of long-term protection after vaccination is likely contributing to increases in pertussis among adolescents

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Article
First Pertussis Vaccine Dose and Prevention of Infant Mortality
Tejpratap S.P. Tiwari, MDa, Andrew L. Baughman, PhD, MPHb, and Thomas A. Clark, MD, MPHa
Author Affiliations
aMeningitis and Bacterial Vaccine Preventable Diseases Branch, Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, and
bDivision of Global HIV/AIDS, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia
Abstract
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.

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Special Article
Strategies to Decrease Pertussis Transmission to Infants
Kevin Forsyth, MD, PhDa, Stanley Plotkin, MDb, Tina Tan, MDc, and Carl Heinz Wirsing von König, MDd
Author Affiliations
aDepartment of Paediatrics and Child Health, Flinders Medical Centre, Flinders University, Adelaide, Australia;
bDepartment of Pediatrics, University of Pennsylvania, Philadelphia, Pennsylvania;
cNorthwestern University, Feinberg School of Medicine, Chicago, Illinois; and
dLabor;Medizin Krefeld MVZ, Krefeld, Germany
Abstract
The Global Pertussis Initiative (GPI) is an expert scientific forum addressing the worldwide burden of pertussis, which remains a serious health issue, especially in infants. This age cohort is at risk for developing pertussis by transmission from those in close proximity. Risk is increased in infants aged 0 to 6 weeks, as they are too young to be vaccinated. Older infants are at risk when their vaccination schedules are incomplete. Infants also bear the greatest disease burden owing to their high risk for pertussis-related complications and death; therefore, protecting them is a high priority. Two vaccine strategies have been proposed to protect infants. The first involves vaccinating pregnant women, which directly protects through the passive transfer of pertussis antibodies. The second strategy, cocooning, involves vaccinating parents, caregivers, and other close contacts, which indirectly protects infants from transmission by preventing disease in those in close proximity. The goal of this review was to present and discuss evidence on these 2 strategies. Based on available data, the GPI recommends vaccination during pregnancy as the primary strategy, given its efficacy, safety, and logistic advantages over a cocoon approach. If vaccination during pregnancy is not feasible, then all individuals having close contact with infants <6 months old should be immunized consistent with local health authority guidelines. These efforts are anticipated to minimize pertussis transmission to vulnerable infants, although real-world effectiveness data are limited. Countries should educate lay and medical communities on pertussis and introduce robust surveillance practices while implementing these protective strategies.

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Commentary
Epidemic Pertussis and Acellular Pertussis Vaccine Failure in the 21st Century
James D. Cherry, MD, MSc
Author Affiliations
Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, California
[Initial text]
In this issue of Pediatrics Acosta et al1 present a tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis, adsorbed (Tdap) vaccine effectiveness study in adolescents in Washington State during the first 6 months of 2012. Their findings support the previous Tdap effectiveness data from Wisconsin.2 The duration of Tdap effectiveness is disappointing, particularly because case-control studies tend to inflate efficacy.3
In 4 recent publications (including 1 article in Pediatrics) I have discussed epidemic pertussis and why vaccines fail.4–7 Before discussing why Tdap vaccine effectiveness wanes so rapidly, it seems worthwhile to discuss how rapidly protection wanes after a natural infection in the pre-Tdap era and to take a realistic look at the resurgence of pertussis.
The resurgence of pertussis is often attributed to the switch from whole-cell pertussis vaccines to acellular products. However, the increase in reported pertussis began ∼14 years before the universal use of diphtheria-tetanus-acellular pertussis (DTaP) vaccines in childhood commenced. The 2 greatest contributors to the resurgence of pertussis are greater awareness and more sensitive diagnosis (the routine use …