Design issues for a big city immunization registry

New York is the nation's largest city, with a birth cohort of more than 130,000 and nearly 2 million children aged 18 years and under. Its sheer size has important implications for registry design, as do the poverty, cultural diversity, and mobility of the population, as well as large numbers of special groups, such as homeless people and recent immigrants. The size and diversity of the provider population also have consequences for immunization registry planning. The private sector is heavily represented-about 55% of the immunizations are given by physicians in private practice, voluntary hospitals, and private clinics. Public and private providers practice in a variety of settings and span all levels of technologic sophistication. This article addresses the ways in which New York City's technical registry design and implementation plan have responded to local requirements and constraints. Topics covered include decisions about roles and responsibilities of central registry reporting and retrieving information, child identifiers collected and match strategies, and policy decisions about security and confidentiality. It is instructive to examine the process and rationale for New York City's design decisions, as well as the decisions themselves. Some of the decisions may in fact be generalizable to other large systems; some of the rejected alternatives may be appropriate under a different set of constraints. The entire decision process demonstrates how a group of planners took a general concept (an immunization registry) and modified it in the course of bringing it to the threshold of implementation, in the summer of 1996.