The reason is that the expression value (point location) of OAS1 is on the linear regression line in the comparison of “COVID-19 vs COVID-19” in heterogeneous samples, but it is an outlier of the regression line and 95% confidence interval in comparison of “COVID-19 vs InfluenzaA/B/RSV” (Figure 6E), indicating an underlying diagnostic classifier of OAS1 in a 14-gene regression model. The gene discussed is OAS1; the disease is COVID-19.