title: Randomised trial of effect of vitamin A supplementation on antibody response to measles vaccine in Guinea-Bissau, west Africa.
abstract: BACKGROUND
  WHO has recommended vitamin A supplementation for children aged 6 months or older in developing countries at the same time as immunisation. One study has reported significantly lower seroconversion ratios among children who have received vitamin A supplements with measles vaccine at age 6 months. The aim of our study was to assess the effect of vitamin A supplementation on antibody response to measles vaccination at age 9 months, which is the more common age for immunisation in developing countries.
  
  
  METHODS
  In an urban community in Guinea-Bissau, we did a randomised, double-blind, placebo-controlled study of the effect of simultaneous vaccination and vitamin A supplementation in 462 children who received either a two-dose schedule of measles vaccine at the ages of 6 months and 9 months (150 infants) or one dose of measles vaccine at age 9 months (312 infants). Children were followed up to the age of 18 months and a blood sample was then collected to assess the antibody response.
  
  
  RESULTS
  397 (86%) of the children took part in the follow-up (52 [11%] had moved and 13 [3%] had died). Among children who received a two-dose vaccine schedule, seroconversion was 98%. There was no difference in seroconversion or geometric mean titre (GMT) for children receiving vitamin A compared with children receiving no supplement. Among children receiving only one dose of measles vaccine at age 9 months, seroconversion was 95%. The GMT was significantly higher in children receiving vitamin A than in those receiving no supplement (3704 vs 2439 mIU; GMT ratio 1.52 [1.22-1.88]). The effect on plasma antibody concentration in the blood was stronger for boys (3902 vs 1916 mIU; GMT ratio 2.04 [1.53-2.72]) than for girls (3502 vs 3017 mIU; GMT ratio 1.16 [0.85-1.58]) who had received vitamin A with measles vaccine. In a multivariate analysis of variance adjusted for sex, vitamin A supplementation was associated with higher antibody titres (p < 0.001). There was a significant interaction between vitamin A supplementation and sex (p = 0.02).
  
  
  CONCLUSIONS
  There is no indication that simultaneous administration of measles vaccine and vitamin A supplements has a negative effect on measles immunity. Among the children who had received two doses of measles vaccine at the ages of 6 months and 9 months, supplements of vitamin A had no significant effect. Among children only receiving one dose of measles vaccine at age 9 months, 100,000 IU vitamin A increased antibody concentrations, especially for boys.
authors.affiliation: Projecto de Saúde de Bandim, Bissau, Guinea Bissau.
authors.forename: C S
authors.initials: CS
authors.lastname: Benn
authors.forename: P
authors.initials: P
authors.lastname: Aaby
authors.forename: C
authors.initials: C
authors.lastname: Balé
authors.forename: J
authors.initials: J
authors.lastname: Olsen
authors.forename: K F
authors.initials: KF
authors.lastname: Michaelsen
authors.forename: E
authors.initials: E
authors.lastname: George
authors.forename: H
authors.initials: H
authors.lastname: Whittle
mesh_terms: D000914:Antibodies, Viral / Q000096:biosynthesis* / Q000097:blood; D001942:Breast Feeding; D003906:Developing Countries; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D005500:Follow-Up Studies; D006169:Guinea-Bissau; D006801:Humans; D007115:Immunization Schedule; D007223:Infant; D008297:Male; D008457:Measles / Q000517:prevention & control*; D008458:Measles Vaccine / Q000008:administration & dosage*; D008459:Measles virus / Q000276:immunology*; D015999:Multivariate Analysis; D010919:Placebos; D012737:Sex Factors; D014611:Vaccination; D014801:Vitamin A / Q000008:administration & dosage / Q000627:therapeutic use*; D014802:Vitamin A Deficiency / Q000188:drug therapy*
chemical_list: D000914:Antibodies, Viral; D008458:Measles Vaccine; D010919:Placebos; D014801:Vitamin A