Party leaders are unquestionably complicit in the premature deaths of their own supporters. No country has a perfect COVID-vaccination rate, even this far into the pandemic, but America’s record is particularly dismal. About a third of Americans—more than a hundred million people—have yet to get their initial shots. You can find anti-vaxxers in every corner of the country. But by far the single group of adults most likely to be unvaccinated is Republicans: 37 percent of Republicans are still unvaccinated or only partially vaccinated, compared with 9 percent of Democrats. Fourteen of the 15 states with the lowest vaccination rates...