Overcoming Reporting Delays Is Critical to Timely Epidemic Monitoring: The Case of COVID-19 in New York City

Harris, J. E.

During a fast-moving epidemic, timely monitoring of case counts and other key indicators of disease spread is critical to an effective public policy response. We describe a nonparametric statistical method - originally applied to the reporting of AIDS cases in the 1980s - to estimate the distribution of reporting delays of confirmed COVID-19 cases in New York City. During June 21 - August 1, 2020, the estimated mean delay in reporting was 5 days, with 15 percent of cases reported after 10 or more days. Relying upon the estimated reporting-delay distribution, we project COVID-19 incidence during the most recent three weeks as if each case had instead been reported on the same day that the underlying diagnostic test had been performed. The statistical method described here overcomes the problem of reporting delays only at the population level. The method does not eliminate reporting delays at the individual level. That will require improvements in diagnostic technology, test availability, and specimen processing.