title: Measles antibody levels after vaccination with Edmonston-Zagreb and Schwarz measles vaccine at 9 months or at 9 and 18 months of age: a serological study within a randomised trial of different measles vaccines.
abstract: Standard-titre Schwarz (SW) and Edmonston-Zagreb (EZ) measles vaccines (MV) are both used in the routine immunisation programme. Within a trial of different strains of MV, we examined antibody responses in both one-dose and two-dose schedules when the first dose was administered at 9 months.
  
  
  METHODS
  The trial was conducted in an urban area in Guinea-Bissau where we have had a health and demographic surveillance system and studied strategies to prevent measles infection since 1978. In the present study, children were randomised to SW or EZ as the first MV and furthermore randomised to a second dose of the same MV or no vaccine at 18 months of age. We obtained blood samples from 996 children at baseline; post-vaccination blood samples were collected at 18 and 24 months of age to assess measles antibody levels after one or two doses of MV.
  
  
  RESULTS
  At age 18 months all had responded to the first dose and only 1% (8/699) of the children had non-protective antibody levels irrespective of vaccine type. SW was associated with significantly higher levels of measles antibodies (geometric mean titre (GMT)=2114 mIU/mL (95%CI 1153-2412)) than EZ (GMT=807 mIU/mL (722-908)) (p=0.001). Antibody concentration was significantly higher in girls than in boys after EZ but not after SW. Antibody levels were higher in the rainy than the dry season. There was no clear indication that a booster dose at 18 months increased the antibody level at 24 months of age.
  
  
  CONCLUSIONS
  Maternal antibody levels have declined significantly in recent years and 99% had protective levels of measles antibody following primary MV at 9 months of age. It is unlikely that measles prevention and child health will be improved by increasing the age of MV as currently recommended.
authors.affiliation: Bandim Health Project, Indepth Network, Apartado 861, Bissau, Guinea-Bissau.
authors.forename: Cesario
authors.initials: C
authors.lastname: Martins
authors.forename: May-Lill
authors.initials: ML
authors.lastname: Garly
authors.forename: Carlitos
authors.initials: C
authors.lastname: Bale
authors.forename: Amabelia
authors.initials: A
authors.lastname: Rodrigues
authors.forename: Christine S
authors.initials: CS
authors.lastname: Benn
authors.forename: Hilton
authors.initials: H
authors.lastname: Whittle
authors.forename: Peter
authors.initials: P
authors.lastname: Aaby
mesh_terms: D000914:Antibodies, Viral / Q000097:blood*; D002675:Child, Preschool; D005260:Female; D006169:Guinea-Bissau; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008457:Measles / Q000517:prevention & control*; D008458:Measles Vaccine / Q000008:administration & dosage* / Q000276:immunology*; D014611:Vaccination / Q000379:methods*
chemical_list: D000914:Antibodies, Viral; D008458:Measles Vaccine
keywords: Antibody response; Edmonston-Zagreb measles vaccine; Non-specific effects of vaccines; Schwarz measles vaccine; Two-dose measles vaccination