title: Impact of the Advisory Committee on Immunization Practices' 4-day grace period in a low-income community.
abstract: BACKGROUND
  In 2002, the Advisory Committee on Immunization Practices (ACIP) recommended vaccine doses administered < or = 4 days before the minimum age or interval be counted as valid. The study objective was to assess the impact of the 4-day grace period on the need for revaccination and associated costs in a low-income community, compared to standard practice (i.e., repeating all doses that fall outside current ACIP guidelines).
  
  
  METHODS
  From 1999 to 2001, semi-annual immunization assessments of 8293 randomly selected children, aged 19-35 months, were conducted at a 16-practice network serving an underserved community in New York City. Outcome measures were rates of antigen-specific invalid doses and number of children needing revaccination, with and without the 4-day grace period. Revaccination costs were based on the Vaccines for Children (VFC) price list.
  
  
  RESULTS
  The 4-day grace period reduced the number of children needing revaccination from 17.1% to 12.0%, a drop of 30%. The rates of invalid doses decreased from 1.9% to 1.3%, a drop of 33%. Invalid doses for hepatitis B (HepB)-2 decreased by two thirds (69.7%); for diphtheria-tetanus-acellular pertussis (DTaP)-1, Haemophilus influenzae type b (Hib)-1 and Hib-3 by half (44.9%-50.0%); for Polio-1, Polio-2, Polio-3, and measles-mumps-rubella (MMR) by one third (31.6%-33.3%); and for DTaP-2, DTaP-3, HepB-3, and varicella by nearly one quarter (20.0%-24.0%). At these rates, revaccinating 100,000 children younger than age 3 years would cost 213,588 dollars per year, compared to 152,539 dollars with the 4-day grace period, in vaccine costs alone.
  
  
  CONCLUSIONS
  In a low-income community, ACIP's 4-day grace period made a significant impact on the number of children requiring revaccination and on revaccination costs. However, the number of children needing revaccination remains high.
mesh_terms: D002675:Child, Preschool; D019983:Guideline Adherence; D006801:Humans; D017589:Immunization Programs / Q000191:economics / Q000592:standards* / Q000706:statistics & numerical data; D007115:Immunization Schedule; D007223:Infant; D009519:New York City; D011203:Poverty / Q000191:economics; D017410:Practice Guidelines as Topic; D014611:Vaccination / Q000191:economics / Q000592:standards*; D014612:Vaccines / Q000008:administration & dosage*
chemical_list: D014612:Vaccines