title: Immunization coverage in a population-based sample of Maryland children.
abstract: OBJECTIVE
  To describe the vaccination coverage of a population-based sample of Maryland children.
  
  
  METHODS
  Historical cohort study using stratified cluster sampling. Strata were formed from five state regions and public and private schools within each region.
  
  
  METHODS
  Random sample of elementary schools in Maryland.
  
  
  METHODS
  Immunization records were obtained for a randomly selected cohort of 1938 first-grade children in Maryland.
  
  
  METHODS
  Age of completion of recommended childhood vaccines and proportion of vaccines given simultaneously.
  
  
  RESULTS
  By first grade, 95.2% of the sample of Maryland children were documented to have received at least four doses of the diphtheria and tetanus toxoids and pertussis (DTP) vaccine, three doses of oral poliovirus (OPV) vaccine, and one dose of measles-mumps-rubella (MMR) vaccine. However, only 54.8% of children surveyed had achieved this level of immunization by 24 months of age. For children whose immunizations were up to date on their first birthday (78.7% of children surveyed), vaccine providers failed to administer one dose of DTP, OPV, and MMR vaccines to 30% of these children during the second year of life. Only 16.2% (n = 313) of children sampled received an MMR vaccination simultaneously with any dose of DTP or OPV vaccine.
  
  
  CONCLUSIONS
  This study shows that while immunization levels are very high at school entry, there are serious delays in vaccine administration before school entry. These delays are observed regardless of whether children are in public or private schools or attend school in an urban, suburban, or rural area. Physicians and health care providers could play an important role in age-appropriate vaccination by administering vaccines simultaneously.
authors.affiliation: Department of Epidemiology, Johns Hopkins University, School of Hygiene and Public Health, Baltimore, Md.
authors.forename: I T
authors.initials: IT
authors.lastname: Williams
authors.forename: D M
authors.initials: DM
authors.lastname: Dwyer
authors.forename: E M
authors.initials: EM
authors.lastname: Hirshorn
authors.forename: R C
authors.initials: RC
authors.lastname: Bonito
authors.forename: N M
authors.initials: NM
authors.lastname: Graham
mesh_terms: D002648:Child; D002675:Child, Preschool; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000008:administration & dosage; D004338:Drug Combinations; D006801:Humans; D007115:Immunization Schedule; D007223:Infant; D008396:Maryland; D008458:Measles Vaccine / Q000008:administration & dosage; D022542:Measles-Mumps-Rubella Vaccine; D009108:Mumps Vaccine / Q000008:administration & dosage; D011055:Poliovirus Vaccine, Oral / Q000008:administration & dosage; D011897:Random Allocation; D012411:Rubella Vaccine / Q000008:administration & dosage; D012494:Sampling Studies; D014611:Vaccination / Q000706:statistics & numerical data*
chemical_list: D015721:Diphtheria-Tetanus-Pertussis Vaccine; D004338:Drug Combinations; D008458:Measles Vaccine; D022542:Measles-Mumps-Rubella Vaccine; D009108:Mumps Vaccine; D011055:Poliovirus Vaccine, Oral; D012411:Rubella Vaccine