title: An Assessment of the Cocooning Strategy for Preventing Infant Pertussis-United States, 2011.
abstract: BACKGROUND
  Infants are at greatest risk for severe pertussis. In 2006, the Advisory Committee on Immunization Practices recommended that adolescents and adults, especially those with infant contact, receive a single dose of Tdap (tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine). To assess the effectiveness of cocooning, we conducted a case-control evaluation of infant close contacts.
  
  
  METHODS
  Pertussis cases aged <2 months with onset between 1 January 2011 and 31 December 2011 were identified in Emerging Infections Program Network sites. For each case, we recruited 3 controls from birth certificates and interviewed identified adult close contacts (CCs) or parents of CCs aged <18 years. Pertussis vaccination was verified through medical providers and/or immunization registries.
  
  
  RESULTS
  Forty-two cases were enrolled, with 154 matched controls. Around enrolled infants, 859 CCs were identified (600 adult and 259 nonadult). An average of 5.4 CCs was identified per case and 4.1 CCs per control. Five hundred fifty-four (64.5%) CCs were enrolled (371 adult and 183 non-adult CCs); 119 (32.1% of enrolled) adult CCs had received Tdap. The proportion of Tdap-vaccinated adult CCs was similar between cases and controls (P = .89). The 600 identified adult CCs comprised 172 potential cocoons; 71 (41.3%) potential cocoons had all identified adult CCs enrolled. Of these, 9 were fully vaccinated and 43.7% contained no Tdap-vaccinated adults. The proportion of fully vaccinated case (4.8%) and control (10.0%) cocoons was similar (P = .43).
  
  
  CONCLUSIONS
  Low Tdap coverage among adult CCs reinforces the difficulty of implementing the cocooning strategy and the importance of vaccination during pregnancy to prevent infant pertussis.
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Amy E
authors.initials: AE
authors.lastname: Blain
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Melissa
authors.initials: M
authors.lastname: Lewis
authors.affiliation: Minnesota Department of Health, St Paul.
authors.forename: Emily
authors.initials: E
authors.lastname: Banerjee
authors.affiliation: Connecticut Department of Public Health, Hartford.
authors.forename: Kathy
authors.initials: K
authors.lastname: Kudish
authors.affiliation: Public Health Division, Oregon Health Authority, Portland.
authors.forename: Juventila
authors.initials: J
authors.lastname: Liko
authors.affiliation: New York State Department of Health, Albany.
authors.forename: Suzanne
authors.initials: S
authors.lastname: McGuire
authors.affiliation: New Mexico Department of Health, Santa Fe.
authors.forename: David
authors.initials: D
authors.lastname: Selvage
authors.affiliation: California Emerging Infections Program, Oakland.
authors.forename: James
authors.initials: J
authors.lastname: Watt
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Stacey W
authors.initials: SW
authors.lastname: Martin
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Tami H
authors.initials: TH
authors.lastname: Skoff
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000008:administration & dosage / Q000276:immunology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D017063:Outcome Assessment, Health Care; D011159:Population Surveillance; D014481:United States / Q000453:epidemiology; D014611:Vaccination; D014917:Whooping Cough / Q000517:prevention & control*
chemical_list: D015721:Diphtheria-Tetanus-Pertussis Vaccine
keywords: Tdap; cocooning; pertussis