9:51 a.m. ET, April 12, 2021 50% of US adults expected to have at least one dose of Covid-19 vaccine by end of this week From CNN's Deidre McPhillips People wait in line at a pop-up Coviid-19 vaccination site in Orlando, Florida, on April 9. Paul Hennessy/SOPA Images/LightRocket/Getty Images If Covid-19 vaccinations continue at the current pace, the United States will likely hit a milestone this week: vaccinating half of adults with at least one dose of vaccine. Over the past week, more than 3.1 million doses of vaccine have been administered each day on average, according to data reported by the US Centers for Disease Control and Prevention. Those doses could be first doses, second doses or single doses.