Evaluation of reporting timeliness of public health surveillance systems for infectious diseases

Timeliness is a key performance measure of public health surveillance systems. The National Notifiable Diseases Surveillance System (NNDSS) data was evaluated to determine if it could support timely notification and state response to multistate outbreaks. When timeliness of NNDSS data was evaluated, the median national reporting delay, based on date of disease onset, ranged from 12 days for meningococcal disease to 40 days for pertussis. Diseases with the longer incubation periods tended to have a higher percentage of cases reported within its incubation period. Our analysis of NNDSS reporting timeliness indicated that among the conditions evaluated (except for acute hepatitis A infection), the long reporting lag and the variability across states limits the usefulness of NNDSS data and aberration detection analysis of those data for identification of and timely response to multistate outbreaks. A more standardized approach for evaluating and describing surveillance system timeliness should be considered. Further evaluation of the factors that contribute to NNDSS reporting timeliness is warranted.