Assessment of the quality of immunization data produced by the national individual registration system in Uruguay, 2006.

Objective: The nominal registration system of Uruguay's national immunization program (NIP) tracks administered vaccines on a paper form filled out after each vaccination and collated into a national database, thus allowing for individual follow-up. This study performed a comprehensive assessment of the quality of Uruguay's immunization data in November 2006 to evaluate the validity of the information and to confirm the high national immunization coverage reported by the program.

Methods: The research team analyzed the concordance of the operational-level numerators (infant immunization data from 18 public and private vaccination centers in six country departments) with department- and national-level data, and compared the national-level (NIP) infant denominators with other official sources. A standardized questionnaire was used to evaluate system performance at the operational (vaccination center), department, and national level. Rapid house-to-house monitoring was conducted to generate additional coverage estimates.

Results: Numerator accuracy throughout the data flow was 100%, and national-level denominators appeared to be exhaustive. Overall system performance was excellent (proper archiving and recording of form data, sufficient supply of forms, timely flow of information, adequate defaulter tracing practices and computer system security). The main weaknesses were the degree of data analysis and feedback to peripheral levels. House-to-house monitoring showed high overall immunization coverage (97%).

Conclusion: Uruguay's NIP registration system produces remarkably reliable information, ensuring valid measurement of immunization coverage. In addition, by allowing for monitoring of each child's current vaccination status, it facilitates management of interventions designed to reduce vaccination default and thus helps achieve the country's high level of coverage.