Shift in supply of masks to the left The supply of masks actually dropped, as many migrant workers who produce the masks were prevented from returning to work. The lack of workers leads to an inward shift of the supply. P S1 P - Price P1 S P1 - Price before the COVID Pe - Price during the COVID Pe Q - Quantity of Demand D Q1 - Quantity of Demand before COVID Qe - Quantity of Demand during COVID Q1 Qe