The Use of a Self-triage Tool to Predict COVID-19 Cases and Hospitalizations in the State of Georgia.

INTRODUCTION: The coronavirus 2019 (COVID-19) pandemic has created significant burden on healthcare systems throughout the world. Syndromic surveillance, which collects real-time data based on a range of symptoms rather than laboratory diagnoses, can help provide timely information in emergency response. We examined the effectiveness of a web-based COVID-19 symptom checking tool (C19Check) in the state of Georgia (GA) in predicting COVID-19 cases and hospitalizations. METHODS: We analyzed C19Check use data, COVID-19 cases, and hospitalizations from April 22-November 28, 2020. Cases and hospitalizations in GA were extracted from the Georgia Department of Public Health data repository. We used the Granger causality test to assess whether including C19Check data can improve predictions compared to using previous COVID-19 cases and hospitalizations data alone. Vector autoregression (VAR) models were fitted to forecast cases and hospitalizations from November 29 - December 12, 2020. We calculated mean absolute percentage error to estimate the errors in forecast of cases and hospitalizations. RESULTS: There were 25,861 C19Check uses in GA from April 22-November 28, 2020. Time-lags tested in Granger causality test for cases (6-8 days) and hospitalizations (10-12 days) were significant (P= <0.05); the mean absolute percentage error of fitted VAR models were 39.63% and 15.86%, respectively. CONCLUSION: The C19Check tool was able to help predict COVID-19 cases and related hospitalizations in GA. In settings where laboratory tests are limited, a real-time, symptom-based assessment tool can provide timely and inexpensive data for syndromic surveillance to guide pandemic response. Findings from this study demonstrate that online symptom-checking tools can be a source of data for syndromic surveillance, and the data may help improve predictions of cases and hospitalizations.