https://www.scientificamerican.com/article/covid-vaccine-rollout-pits-fairness-against-speed/ > COVID vaccines were developed with record-breaking speed. But their distribution has been anything but quick. As of Monday morning, about 47 percent of the doses distributed to states had not been administered, according to data from the U.S. Centers for Disease Control and Prevention. This means that a month into the distribution effort, only about 6 percent of people in the U.S. have received at least one dose of the two-dose vaccines that are now available. Anthony Fauci, the nation’s top infectious diseases expert, estimates that up to 90 percent of the U.S. population needs to be vaccinated to reach herd immunity—the point at which so many people are protected from the disease that it peters out. > In an effort to pick up the pace, many states have expanded access to a COVID vaccine to everyone aged 65 and older, people with medical conditions that put them at high risk of the disease and certain essential workers. But the hodgepodge of policies and priorities in different states and the lack of unified infrastructure has caused chaos and confusion for people eager to get their shot. Many of the country’s most vulnerable people are encountering busy phone lines, crashing Web sites, byzantine online registration portals and long lines at vaccination sites, prompting concerns that the expanded rollout could worsen the racial and economic inequalities laid bare by the COVID-19 pandemic.