2022-07-05-世界卫生组织-Immunization_United_States_of_America_2022_country_profile_18页_355kb

WHO and UNICEF Immunization Coverage Estimates for the United States (2010-2021)

Introduction:
WHO and UNICEF collaborate to estimate national immunization coverage based on empirical data from member states, including submitted reports, surveys, and administrative records. For the United States, estimates rely heavily on annual surveys like the National Immunization Survey-Child (NIS-Child), population data, and local jurisdictional assessments. Coverage levels are analyzed for specific vaccines and years, with a focus on doses like DTP1, DTP3, BCG, MCV1, MCV2, IPV1, HepB, Hib, Pol3, RCV1, HepB3, MCV1, RotaC, and PcV3. Estimates for 2020 are noted to potentially overestimate coverage due to COVID-19 disruptions, which caused declines in vaccination rates in several US regions.

Methodology and Data Sources:
The 2011 revision introduced a grade of confidence (GoC) to assess data reliability, distinguishing between strong empirical support (GoC •••) and weaker evidence (GoC • or No accepted empirical data). Primary data sources include national surveys (e.g., NIS-Child), where coverage is derived from children's age-based cohorts and historical vaccination records. Administrative and official assessments supplement these, but data quality varies, and adjustments may interpolate missing years. Survey results and historical data analyzed via Kaplan Meier methods ensure coverage estimates reflect timely immunization, though potential biases exist in numerators and denominators.

Key Findings and Trends:
Coverage remained high throughout the period, typically ranging from 90% to 98%, with DTP3 showing 98% in 2010-2019. BCG coverage was consistently above 97%, and Pol3 coverage varied slightly but remained strong (e.g., 93% in 2019). IPV1 estimates began in 2015, emphasizing the shift to inactivated polio vaccine. For vaccines like HepB3 and Hib3, coverage exceeded 90%, indicating robust immunization infrastructure. COVID-19 impacts in 2020 led to overestimated values, with declines of nearly 15% in some vaccines due to program disruptions. Trends show sustained high coverage despite challenges, highlighting the US's effective immunization system.

Limitations and Recommendations:
Estimates are extrapolated from reported data, and without probability models, confidence intervals are not provided. Potential biases in data, such as misreporting or sample limitations, may skew results. WHO and UNICEF advise caution, emphasizing that these estimates should be contextualized for specific applications. Data from sources like the UN Population Division and national assessments can be unreliable, requiring careful interpretation. COVID-19 disruptions in 2020 underscore the need for real-time monitoring to adjust strategies and ensure accurate coverage tracking.

Conclusion:
Overall, the US demonstrates high immunization coverage, with comprehensive data reviews and surveillance mitigating risks. Future revisions (e.g., July 2023) will incorporate updated data, improving the accuracy of global immunization assessments.