2023-07-16-世界卫生组织-Immunization_Belgium_2023_country_profile_28页_361kb

WHO and UNICEF National Immunization Coverage Estimates Summary

Core Content

The World Health Organization (WHO) and United Nations Children's Fund (UNICEF) jointly estimate national immunization coverage levels for various vaccines across different years. These estimates are based on data from Member States, which may include administrative reports, official assessments, and survey-based information. The goal is to provide a reliable measure of immunization coverage, even when data are incomplete or potentially biased.

Main Points

• Estimation Process:

  • WHO and UNICEF review data from Member States and consider potential biases and expert opinions.
  • Estimates are made country-specific, without borrowing data from other countries.
  • In cases of missing data, interpolation is used based on available data from earlier and later years.
  • For mixed data sources, the most likely estimate is selected, taking into account potential biases.

• Types of Coverage Data:

  • Administrative Coverage: Based on aggregated reports from health providers, potentially biased due to inaccurate numerator or denominator data.
  • Official Coverage: Reflects national authorities' assessment, which may combine administrative, survey, or other data sources.
  • Survey Coverage: Derived from population-based household surveys of children aged 12–23 months or 24–35 months, using vaccination history or caregiver recall.

• Grade of Confidence (GoC):

  • GoC is used to indicate the level of empirical support for estimates.
  • GoC is not a judgment of data quality but rather the degree of support from various data sources.
  • Three levels of GoC are described:
    • [R+ D+ S+]: Estimate supported by reported data, independent denominator, and at least one supporting survey within 2 years.
    • [R+ D+ S-]: Estimate supported by at least one data source, with no data challenging the estimate.
    • [R- D- S-]: No direct supporting data or data challenging the estimate.

• Vaccine-Specific Coverage:

  • BCG: Percentage of births who received one dose of the Bacillus Calmette Guerin vaccine.
  • DTP1 / DTP3: Percentage of surviving infants who received the 1st or 3rd dose of diphtheria and tetanus toxoid with pertussis vaccine.
  • Pol3: Percentage of surviving infants who received the 3rd dose of polio vaccine, regardless of type.
  • IPV1: Percentage of surviving infants who received at least one dose of inactivated polio vaccine (IPV), depending on the national immunization schedule.
  • MCV1 / MCV2: Percentage of surviving infants who received the 1st or 2nd dose of measles containing vaccine (MCV).
  • RCV1: Percentage of surviving infants who received the 1st dose of rubella containing vaccine, based on the first MCV-RCV combination.
  • HepBB: Percentage of births who received a dose of hepatitis B vaccine within 24 hours of delivery, only for countries with a universal birth dose policy.
  • HepB3: Percentage of surviving infants who received the 3rd dose of hepatitis B vaccine.
  • Hib3: Percentage of surviving infants who received the 3rd dose of Haemophilus influenzae type b vaccine.
  • RotaC: Percentage of surviving infants who received the final recommended dose of rotavirus vaccine.
  • PcV3: Percentage of surviving infants who received the 3rd dose of pneumococcal conjugate vaccine.
  • YFV: Percentage of surviving infants who received one dose of yellow fever vaccine in countries where it is part of the national schedule or recommended in at-risk areas.

Key Information

• Estimates for Belgium (BEL):

  • The summary includes data for DTP1, DTP3, and other vaccines from 2011 to 2022.
  • Coverage levels are generally high, with most estimates ranging from 97% to 100%.
  • GoC for all years is ●●, indicating high empirical support.
  • Official coverage is close to the Estimate, with only minor variations.
  • Administrative and Survey data are not available for most years, marked as NA.

• Data Sources:

  • Estimates are primarily based on reported data and population weighted regional surveys.
  • Stable coverage assumption is often used when no recent survey data is available.
  • For IPV1, the estimate reflects coverage with at least one routine dose of IPV in countries with different immunization schedules.

• Disclaimer:

  • All data are provided with no warranty, and users are advised to use estimates with caution.
  • The GoC reflects empirical support, not the quality of data reported by national authorities.

Summary Table (Belgium - DTP1 and DTP3)