Fig. 2
From: COVID-19 outbreaks surveillance through text mining applied to electronic health records
Time series of suspected and confirmed cases of COVID-19. The bars represent the daily numbers of suspected (in blue) and confirmed (in orange) cases of COVID-19. Here, we consider only cases with ages 18 years. The solid lines represent moving averages with windows of 7 days for both quantities. The time series are divided into three epidemiological waves: The first occurred between January 2020 and November 2020, the second between November 2020 and November 2021, and the third between November 2021 and May 2022. We note that the time series of suspected cases of COVID-19 is delayed in comparison to the time series of confirmed cases of COVID-19, endorsing the idea that it is possible to early detect COVID-19 waves using only the patient's reported symptoms