Study Objectives
COVID-19 was initially detected in Wuhan, China, and has since spread throughout the world. In the United States, Washington State was the first state affected but by March 2020, New York and New Jersey were the two states with the greatest number of cases. We had previously instituted an ongoing syndromic surveillance system (SSS) in 35 hospitals in New York and New Jersey. Our goal was to investigate whether monitoring the respiratory emergency department (ED) visits by syndromic surveillance could be used to follow the incidence of COVID-19 in our area.
Methods
This was a retrospective cohort of consecutive ED visits. It took place at 35 hospitals within 200 miles of New York City from January 1, 2019 through May 15, 2020.Protocol: We identified respiratory visits using a “RESP” syndrome filter for patients’ chief complaints developed for the New York State Department of Public Health. We used the CUSUM28 Statistic to identify a “signal” day. We defined a “signal” day as the day when “RESP” daily visits exceeded the 28-day moving average plus 3 times the 28-day moving average standard deviation. We also plotted the percent of total ED visits that were “RESP” visits.
Results
The database contained 2,302,432 total ED visits of which 305,512 were “RESP” visits. The first signal day in 2020 occurred on March 10. The twenty-eight day moving average of “RESP” visits on March 10 and the number of “RESP” visits on March 10 were 658 and 953, respectively. The peak number of “RESP” visits, 1252, occurred on March 30. See figure for percent of total ED visits for “RESP” visits.
Conclusion
In hospital EDs within 200 miles of New York City syndromic surveillance of ED respiratory visits showed a marked increase in the beginning of March and peaked at the end of March. This mirrored the pattern of COVID-19 cases in our area. Syndromic surveillance of ED respiratory visits may be useful in monitoring COVID-19 in other settings.
