Dr. Anthony Fauci says he would “settle” for a COVID-19 vaccine that’s 70% to 75% effective, but that this incomplete protection, coupled with the fact that many Americans say they won’t get a coronavirus vaccine, makes it “unlikely” that the US will achieve sufficient levels of immunity to quell the outbreak. With government support, three coronavirus vaccines are expected to be studied in large-scale clinical trials in the next three months. “The best we’ve ever done is measles, which is 97 to 98 percent effective,” said Fauci, the director of the National Institute of Allergy and Infectious Diseases. “That would...