title: Measuring the effects of pneumococcal conjugate vaccine (PCV7) on Streptococcus pneumoniae carriage and antibiotic resistance: the Palestinian-Israeli Collaborative Research (PICR).
abstract: BACKGROUND
  The Palestinian-Israeli Collaborative Research (PICR) cross-conflict setting provided a unique opportunity to study overall and indirect effects of pneumococcal conjugate vaccine (PCV7), in two closely related Palestinian populations governed by two distinct health authorities with distinct vaccination policies. Here, PCV7 effects on pneumococcal carriage, serotype distribution and antibiotic resistance are reported.
  
  
  METHODS
  Annual cross-sectional surveys of pneumococcal carriage were performed during 2009-2011 among Palestinian children (≤5 years) (a) under Palestinian-Authority (PA) health policy (Ramallah, Nablus and Bethlehem), where PCV7 was unlicensed (b) under Israeli health policy (East-Jerusalem (EJ)) where PCV7 was rapidly implemented from July 2009. Clinical data were collected, pneumococci identified and characterized for antibiotic susceptibilities and serotype. Analyses included multivariate logistic models with an interaction term for PCV7-effect.
  
  
  RESULTS
  Altogether, 2755 children from PA (n=1772) and EJ (n=983) were enrolled, of which ~30% were pneumococcal carriers. While overall carriage was not affected by vaccination policy, carriage of vaccine-type (VT7) strains decreased from 52% to 22% (p<0.001) in EJ, where PCV was implemented, but not in PA. This was accompanied by an increase in non-VT13 strains from 34% to 65% (p<0.001) in EJ, but not in PA. Furthermore, within two years post-PCV7 introduction, proportion of multi-drug resistant strains, which was initially 23% in both populations, decreased significantly in EJ, to 10%, while simultaneously it increased in PA to 33% (p<0.001). Similar trends were observed for resistance to most antibiotic groups. The proportion of resistant isolates among non-VT13 strains did not change during the study period.
  
  
  CONCLUSIONS
  The unique study design distinguishes secular and seasonal effects from true vaccine effects. While PCV7 did not affect overall pneumococcal carriage rate, VT7 strains, many of which were antibiotic resistant decreased and were replaced by non-VT13 strains, which were mostly not antibiotic resistant, resulting in a net decrease in antibiotic resistance.
authors.affiliation: Maccabi Healthcare Services, Jerusalem-Hashfela District, Israel; Hadassah University Medical Center, Jerusalem, Israel.
authors.forename: Muhannad
authors.initials: M
authors.lastname: Daana
authors.affiliation: Infectious Disease Unit, Sheba Medical Center, Ramat-Gan, Israel.
authors.forename: Galia
authors.initials: G
authors.lastname: Rahav
authors.affiliation: Private Clinic, Nablus, Palestine.
authors.forename: Ayob
authors.initials: A
authors.lastname: Hamdan
authors.affiliation: Private Clinic, Ramallah, Palestine.
authors.forename: Amin
authors.initials: A
authors.lastname: Thalji
authors.affiliation: Private Clinic, Bethlehem, Palestine.
authors.forename: Fuad
authors.initials: F
authors.lastname: Jaar
authors.affiliation: Al-Quds Nutrition and Health Research Institute, Al-Quds University, Abu-Dis, Palestine.
authors.forename: Ziad
authors.initials: Z
authors.lastname: Abdeen
authors.affiliation: Infectious Disease Unit, Sheba Medical Center, Ramat-Gan, Israel.
authors.forename: Hanaa
authors.initials: H
authors.lastname: Jaber
authors.affiliation: Infectious Disease Unit, Sheba Medical Center, Ramat-Gan, Israel; Section of Infectious Disease Epidemiology, Gertner Institute for Epidemiology Research, Ramat-Gan, Israel.
authors.forename: Aviva
authors.initials: A
authors.lastname: Goral
authors.affiliation: Section of Infectious Disease Epidemiology, Gertner Institute for Epidemiology Research, Ramat-Gan, Israel.
authors.forename: Amit
authors.initials: A
authors.lastname: Huppert
authors.affiliation: Maccabi Healthcare Services, Jerusalem-Hashfela District, Israel.
authors.forename: Meir
authors.initials: M
authors.lastname: Raz
authors.affiliation: Infectious Disease Unit, Sheba Medical Center, Ramat-Gan, Israel; Section of Infectious Disease Epidemiology, Gertner Institute for Epidemiology Research, Ramat-Gan, Israel. Electronic address: gregev@hsph.harvard.edu.
authors.forename: Gili
authors.initials: G
authors.lastname: Regev-Yochay
mesh_terms: D000293:Adolescent; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D002353:Carrier State; D002648:Child; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009305:Nasopharynx / Q000276:immunology / Q000382:microbiology; D011008:Pneumococcal Infections / Q000188:drug therapy / Q000453:epidemiology / Q000276:immunology* / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000276:immunology*; D015995:Prevalence; D065288:Serogroup; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects / Q000276:immunology*; D018074:Vaccines, Conjugate / Q000276:immunology*
chemical_list: D000900:Anti-Bacterial Agents; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate
keywords: Antibiotic resistance; PCV7 effects; Pneumococcal carriage; Population-based study