As cases tumble and states reopen, the potential final stage in the U.S. campaign to vanquish COVID-19 is turning into a slog, with a worrisome variant gaining a bigger foothold and lotteries and other prizes failing to persuade some Americans to get vaccinated. … While two of the states slammed hardest by the disaster, California and New York, celebrated their reopenings this week with fireworks and a multimillion-dollar drawing, hospitalizations in parts of Missouri are surging and cases are rising sharply in Texas, illustrating the challenges the country faces this summer.