That World War 2 was a crisis that demanded common and united action against Hitler and the Nazis from Germans? Nothing in her statement says she's referring to past successes, just past challenges for Germany.

Unlike here in the US, I know for a fact that Germans are taught to reckon with the shame of their past in school. Germany has laws against Holocaust denial, and while this cannot be called that, I very much doubt Merkel, of all people, was making the case that Germans must put as much effort into stopping the Coronavirus as they did to win WWII.