2022-07-05-世界卫生组织-Immunization_Bahrain_2022_country_profile_16页_340kb

WHO and UNICEF National Immunization Coverage Estimates Summary

Core Content

WHO and UNICEF jointly estimate national immunization coverage to provide a consistent and reliable picture of vaccine uptake across countries. These estimates are based on a variety of data sources and are adjusted for potential biases. The methodology considers administrative, official, and survey data, and when necessary, interpolates missing data or uses empirical support to determine the most likely coverage levels.

Key Information

Definitions of Coverage Types

• Administrative coverage: Based on reports from national authorities using aggregated data from health service providers. May be biased due to inaccuracies in numerator or denominator data.
• Official coverage: Estimated by national authorities, combining administrative, survey, or other data sources. Reflects their best judgment of the most likely coverage.
• Survey coverage: Derived from population-based household surveys among children aged 12-23 or 24-35 months. Based on documented evidence or caregiver recall.

Vaccine-Specific Coverage Definitions

• BCG: Percentage of births who received one dose of the Bacillus Calmette-Guérin vaccine.
• DTP1: Percentage of surviving infants who received the first dose of diphtheria and tetanus toxoid with pertussis vaccine.
• DTP3: Percentage of surviving infants who received the third dose of the same vaccine.
• Pol3: Percentage of surviving infants who received the third dose of a polio-containing vaccine (either oral or inactivated).
• MCV1: Percentage of surviving infants who received the first dose of measles-containing vaccine, based on the national schedule.
• RCV1: Percentage of surviving infants who received the first dose of rubella-containing vaccine, based on the first measles-rubella combination vaccine.
• HepB3: Percentage of surviving infants who received the third dose of hepatitis B vaccine following the birth dose.
• Hib3: Percentage of surviving infants who received the third dose of Haemophilus influenzae type b vaccine.
• RotaC: Percentage of surviving infants who received the final recommended dose of rotavirus vaccine (either 2nd or 3rd depending on vaccine).
• PcV3: Percentage of surviving infants who received the third dose of pneumococcal conjugate vaccine, based on the national schedule.
• IPV1: Percentage of surviving infants who received at least one dose of inactivated polio vaccine, particularly relevant in countries transitioning from OPV to IPV.

Grade of Confidence (GoC)

• GoC=R+ D+ S+: Estimate is supported by reported data, recalculated with an independent denominator, and at least one supporting survey within 2 years.
• GoC=R+ D+: Estimate is supported by at least one data source (report, denominator, or survey) and no data source challenges it.
• GoC=R- D- S-: Estimate is not well supported and may be challenged by data sources.

Methodology

• WHO and UNICEF do not use probability models to estimate coverage.
• Classical uncertainty measures like confidence intervals are not presented.
• Subjective plausibility ranges are not used.
• Estimation is based on empirical support and data consistency.
• In cases of missing data, interpolation from nearby years is used.
• For countries with no data, estimates are based on administrative data and recalculated with an independent denominator.

Main Points

• Coverage estimates are country-specific and based on a combination of data sources.
• Administrative data are the primary source, but may be biased.
• Survey data are used to validate and support estimates, especially in recent years.
• GoC is used to reflect the degree of empirical support, not the quality of data reported.
• Estimates for IPV1 began in 2015 due to the Polio Eradication and Endgame Strategic Plan.
• Data from 2010 to 2021 for most vaccines are consistently around 98-99%, with some fluctuations.
• Official and Administrative coverage levels are generally close to estimates, but may differ due to reporting and policy changes.
• Survey data are often not available for recent years, leading to reliance on other data sources.
• Recommendations include using high-quality independent assessments to confirm reported coverage levels, especially when data are limited or show potential biases.

Summary Table (Selected Vaccines)

Notes

• Coverage levels are generally high, with most vaccines at 98-99%.
• GoC varies, but most estimates are R+ D+ or R+ D+ S+.
• Some years show challenges from data sources (e.g., D-), leading to lower confidence in the estimates.
• IPV1 estimates began in 2015, reflecting a strategic shift in immunization schedules.
• The data often lack independent survey assessments, especially in recent years.
• The estimates should be used with caution and evaluated based on the specific objective.