2022-07-05-世界卫生组织-Immunization_Bhutan_2022_country_profile_17页_363kb

WHO and UNICEF Immunization Coverage Estimates Summary

Core Content

The World Health Organization (WHO) and United Nations Children's Fund (UNICEF) jointly estimate national immunization coverage levels based on data from Member States. These estimates are not based on ad hoc adjustments but are derived from empirical data, with due consideration to potential biases and expert opinions. The estimates are country-specific, meaning data are not borrowed from other countries unless no data are available. When data are missing, interpolation methods are used to estimate coverage for the missing years.

Main Viewpoints

• Estimates are not based on a probability model and therefore do not include classical measures of uncertainty like confidence intervals.
• Grade of Confidence (GoC) is used to describe the level of empirical support for each estimate. It reflects the degree of support from data sources, not the quality of data reported by national authorities.
• Administrative data are reported by national authorities and may be biased due to inaccuracies in numerator or denominator data.
• Official coverage is an estimate reported by national authorities that may combine administrative, survey, or other data sources.
• Survey-based coverage is derived from population-based household surveys of children aged 12–23 or 24–35 months, and it reflects vaccination history or caregiver recall.
• Estimates for certain vaccines (e.g., HepB3, Hib3, RotaC, PcV3) may vary based on the immunization schedule and the availability of data.

Key Information

Vaccine-Specific Coverage Estimates

Grade of Confidence (GoC) Overview

• GoC = ●●● indicates strong support from data sources.
• GoC = ●● indicates moderate support.
• GoC = ● indicates limited support.
• GoC = R+ D+ S+ means supported by reported data, recalculated denominator, and at least one supporting survey within 2 years.
• GoC = R+ D+ means supported by reported data and recalculated denominator.
• GoC = R+ S+ means supported by reported data and at least one supporting survey.
• GoC = R- D- S- means challenged by data sources.

Notes on Data Sources and Challenges

• Administrative data are used as a primary source, but they may be inaccurate.
• Survey data are used when available and provide more reliable estimates.
• Official data reflect national authorities' assessments and may use multiple data sources.
• In some years, coverage estimates are based on interpolation or re-introduction of vaccines (e.g., DTP-HepB-Hib combination vaccine in 2011, IPV in 2015).
• Fluctuations in target population of surviving infants are noted for some years, which may affect the accuracy of coverage estimates.
• No nationally representative survey within 5 years is a common challenge for recent years (2018–2021), leading to recommendations for improved data collection.

Disclaimer

The WHO and UNICEF estimates are based on varying data quality and are not guaranteed to be accurate. They should be used with caution and assessed according to the specific objective. No liability is assumed for any use of the data.