You observed A ("welding doors shut"), then you observed B ("spread of the virus stopped"). I'm sure we can all agree that both the extent of 'A' and the extent

You observed A ("welding doors shut"), then you observed B ("spread of the virus stopped"). I'm sure we can all agree that both the extent of 'A' and the extent of 'B' are not just unknown, but highly politicized and subject to a massive amount of misinformation. Even with perfect information, it would be unscientific to infer that A caused B.