title: Measles vaccine immunogenicity and antibody persistence in 12 vs 15-month old infants.
abstract: OBJECTIVE
  Maternal measles immunity in the United States today is primarily vaccine induced, with corresponding lower antibody titers in infants, as compared to infants born in an earlier era to mothers with naturally acquired measles immunity. We hypothesized that, due to lower titer of passively transferred maternal measles antibody, administration of measles vaccine at 12 months of age would result in seroconversion and antibody persistence comparable to vaccination at 15 months of age.
  
  
  METHODS
  Children at both an urban hospital and a suburban clinic.
  
  
  METHODS
  Informed consent was obtained from mothers for the infants to receive M-M-R(R)II vaccine at either 12 or 15 months and to have serum samples obtained before vaccination and 4 weeks post-vaccination (PV). Between 9 and 39 months PV, a third serum sample was obtained from 28% of seroconverters. A diary of adverse experiences was kept for 3 weeks PV. Sera were assayed by a microneutralization assay (NT) and an enzyme immunoassay (EIA) for measles antibody.
  
  
  RESULTS
  Both age groups tolerated vaccination well with minor and transient side effects. Forty-four of 47 (94%) 12-month-old infants seroconverted by NT, compared to 45 of 46 (98%) 15-month-olds (p=NS). There was no statistically significant decline in median NT titers or EIA titers in nineteen 12-month-olds and thirteen 15-month olds followed for 9-39 months PV.
  
  
  CONCLUSIONS
  This study showed comparable serologic responses in 12- vs 15-month-old infants born to measles vaccine-immune mothers; however, the sample size was too small to have adequate power and further study is indicated. Titers of antibody were constant in both the 12-month-old and the 15-month-old infants, over a 9-39 month period, suggesting that waning immunity over this period of time is not a problem in either age group.
authors.affiliation: Department of Pediatrics, University of Colorado, Denver, USA. johnson.candice@TCHDEN.ORG
authors.forename: C E
authors.initials: CE
authors.lastname: Johnson
authors.forename: A
authors.initials: A
authors.lastname: Darbari
authors.forename: D S
authors.initials: DS
authors.lastname: Darbari
authors.forename: D
authors.initials: D
authors.lastname: Nalin
authors.forename: J
authors.initials: J
authors.lastname: Whitwell
authors.forename: L W
authors.initials: LW
authors.lastname: Chui
authors.forename: M A
authors.initials: MA
authors.lastname: Cleves
authors.forename: M L
authors.initials: ML
authors.lastname: Kumar
mesh_terms: D000367:Age Factors; D000914:Antibodies, Viral / Q000097:blood; D005260:Female; D006801:Humans; D007112:Immunity, Maternally-Acquired; D007115:Immunization Schedule; D007116:Immunization, Passive; D007223:Infant; D008458:Measles Vaccine / Q000008:administration & dosage* / Q000276:immunology*; D008459:Measles virus / Q000276:immunology; D022542:Measles-Mumps-Rubella Vaccine; D009108:Mumps Vaccine / Q000008:administration & dosage / Q000276:immunology; D011247:Pregnancy; D012411:Rubella Vaccine / Q000008:administration & dosage / Q000276:immunology; D017778:Vaccines, Combined / Q000008:administration & dosage / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; D008458:Measles Vaccine; D022542:Measles-Mumps-Rubella Vaccine; D009108:Mumps Vaccine; D012411:Rubella Vaccine; D017778:Vaccines, Combined