Europe’s elected leaders, French President Emmanuel Macron and Ms. Merkel in particular, are responsible for the tragedy of errors that has caused Europe’s vaccine fiasco. They and their parties are starting to pay the political price.

In mid-March regional elections, Merkel’s Christian Democrat Union had its worst-ever showing in two of its historical strongholds. In the southwestern state of Baden-Württemberg, which the CDU ruled for 58 years until 2011, Ms. Merkel’s party won only 23% of the vote. In Rhineland-Palatinate in the West, once the launchpad for the CDU’s Helmut Kohl, the party finished at 26%, far behind the center-left Social Democrats.

The CDU is sliding in national polls, too. The bungled vaccination program, corruption scandals and regional defeats all reopen the battle to succeed Ms. Merkel when she retires after the election. In January, the CDU’s membership elected Armin Laschet as party leader, but he will face a challenge from Markus Söder of the CDU’s Bavarian sister party, the Christian Social Union, which is less centrist than Ms. Merkel and Mr. Laschet. This isn’t the legacy Ms. Merkel, in office since 2005, had in mind.