Fig. 4.

Illustrating the predictive ability of the NPI-LSTM model. Actual and projected cases are shown for four sample countries. The model predicts the number of cases accurately for the first 14 days where it can be compared with the actual future data (between the vertical lines). The prolonged 180-day predictions are also meaningful, reducing the number of cases to zero with stringent NPIs, and predicting a major increase followed by an eventual decrease with less stringent NPIs. Thus, with proper constraints, data-driven machine learning models can be surprisingly accurate in predicting the progress of the pandemic even with limited data.