title: PCV13-vaccinated children still carrying PCV13 additional serotypes show similar carriage density to a control group of PCV7-vaccinated children.
abstract: In addition to reducing vaccine-type nasopharyngeal carriage rates, pneumococcal conjugate vaccines (PCVs) may decrease carriage density in vaccinated individuals still carrying vaccine serotypes. However, reduction of carriage density has not been systematically studied. This study compared the effect of PCV13 versus PCV7 on carriage density of the serotypes in PCV13 that are not included in PCV7.
  
  
  
  This randomized, double-blind study was conducted in southern Israel and included Jewish and Bedouin subjects. Per protocol, 881 and 873 infants received PCV13 and PCV7, respectively, at ages 2, 4, 6, and 12months. Nasopharyngeal cultures at ages 7, 12, 13, 18, and 24months were plated using the 4-quadrant semiquantitative method and graded 0 (negative) to 4 (growth in all plate quadrants). In this post hoc analysis, the least squares means of cumulative colonization densities per serotype and serotype combination of the total population and each ethnic subpopulation in each vaccine group were calculated, and differences between vaccine groups derived from a linear model.
  
  
  
  PCV13-vaccinated children still carrying the 6 additional PCV13 serotypes unique to PCV13 showed no significant differences in carriage density compared with the PCV7-vaccinated control group. No differences in carriage density were shown between Jewish and Bedouin subpopulations despite higher carriage rates among Bedouin subjects.
  
  
  
  Although PCV13 vaccination reduces vaccine-type carriage compared with PCV7 vaccination by reducing nasopharyngeal acquisition of the additional PCV13 serotypes as previously reported, the current study lacks evidence of a decrease in carriage density of these serotypes when acquired in vaccinated children. Despite the lack of effect on carriage density observed, surveillance data suggest a dramatic decrease in disease rates after PCV implementation. Thus, the current analysis suggests that PCV's impact on carriage density has minimal or no impact on vaccine success. (www.ClinicalTrials.gov: NCT00508742).
authors.affiliation: Faculty of Health Sciences, Ben-Gurion University of the Negev, POB 151, Beer-Sheva 84101, Israel. Electronic address: rdagan@bgu.ac.il.
authors.forename: Ron
authors.initials: R
authors.lastname: Dagan
authors.affiliation: Pfizer Pharma GmbH, Linkstrasse 10, 10785 Berlin, Germany. Electronic address: Christine.Juergens@pfizer.com.
authors.forename: Christine
authors.initials: C
authors.lastname: Juergens
authors.affiliation: inVentiv Health Clinical, 504 Carnegie Center, Princeton, NJ 08540, USA. Electronic address: james.trammel@inventivhealth.com.
authors.forename: James
authors.initials: J
authors.lastname: Trammel
authors.affiliation: Pfizer Inc, 500 Arcola Road, Collegeville, PA 14926, USA. Electronic address: Scott.Patterson@Pfizer.com.
authors.forename: Scott
authors.initials: S
authors.lastname: Patterson
authors.affiliation: Faculty of Health Sciences, Ben-Gurion University of the Negev, POB 151, Beer-Sheva 84101, Israel; Pediatric Infectious Disease Unit, Soroka University Medical Center, POB 151, Beer-Sheva 84101, Israel. Electronic address: dudi@bgu.ac.il.
authors.forename: David
authors.initials: D
authors.lastname: Greenberg
authors.affiliation: Faculty of Health Sciences, Ben-Gurion University of the Negev, POB 151, Beer-Sheva 84101, Israel; Pediatric Infectious Disease Unit, Soroka University Medical Center, POB 151, Beer-Sheva 84101, Israel. Electronic address: givon@bgu.ac.il.
authors.forename: Noga
authors.initials: N
authors.lastname: Givon-Lavi
authors.affiliation: Faculty of Health Sciences, Ben-Gurion University of the Negev, POB 151, Beer-Sheva 84101, Israel; Pediatric Infectious Disease Unit, Soroka University Medical Center, POB 151, Beer-Sheva 84101, Israel. Electronic address: npurat@bgu.ac.il.
authors.forename: Nurith
authors.initials: N
authors.lastname: Porat
authors.affiliation: Pfizer Inc, 401 N. Middletown Road, Pearl River, NY 10965, USA. Electronic address: Bill.Gruber@Pfizer.com.
authors.forename: William C
authors.initials: WC
authors.lastname: Gruber
authors.affiliation: Pfizer Inc, 500 Arcola Road, Collegeville, PA 14926, USA. Electronic address: Dan.scott@Pfizer.com.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Scott
mesh_terms: D018912:Arabs; D058491:Bacterial Load / Q000276:immunology; D002353:Carrier State / Q000276:immunology* / Q000382:microbiology; D002675:Child, Preschool; D004311:Double-Blind Method; D005260:Female; D000069443:Heptavalent Pneumococcal Conjugate Vaccine / Q000008:administration & dosage*; D006801:Humans; D007223:Infant; D007585:Jews; D008297:Male; D009305:Nasopharynx / Q000276:immunology / Q000382:microbiology; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D011018:Pneumonia, Pneumococcal / Q000208:ethnology / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control*; D065288:Serogroup; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects* / Q000254:growth & development / Q000276:immunology; D018074:Vaccines, Conjugate
chemical_list: C538862:13-valent pneumococcal vaccine; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate
keywords: Density; Indirect protection; Nasopharyngeal carriage; Pneumococcal conjugate vaccine; Streptococcus pneumoniae