(CNN)Twenty four states have seen an uptick of at least 10% in Covid-19 cases over the past week as health experts and the federal government keep pressing for more people to get vaccinated. The rapid spread of the Delta variant of the coronavirus has only ratcheted up the pressure. We should think about the Delta variant as the 2020 version of Covid-19 on steroids," Andy Slavitt, a former senior adviser to Joe Biden's Covid Response Team, told CNN on Wednesday. "It's twice as infectious. Fortunately, unlike 2020, we actually have a tool that stops the Delta variant in its tracks:...