YugabyteDB is an open source, high-performance distributed SQL database inspired by Google Spanner. It uses PostgreSQL's standard source code for its SQL and stored procedure functionality, with modifications to support a scalable and fault-tolerant design. The database can be used to analyze COVID-19 data using the YSQL aggregate function regr_r2() which implements a measure called "R-squared" that estimates how much of the dependence between two variables is explained by a linear relationship. A study was conducted using this function on COVIDcast data, which showed a correlation between mask-wearing and incidence of COVID-like symptoms, with an average R-squared value greater than 60% over a 50-day period, indicating that wearing a mask may inhibit the spread of COVID.