According to the CENTERS for Disease Control and Prevention, the number of new coronavirus cases in the United States has dropped from a high in September, but as of Thursday, only about 56 percent of Americans were fully vaccinated. Biden's mandatory vaccination mandate, announced in early September, was met with skepticism and opposition from business groups and Republican governors. Some public health experts worry that the outbreak could worsen if vaccination rates continue to rise as winter sets in and people stay indoors more.