Why is the US vaccination effort lagging behind?

Available for over a year

The US had planned to vaccinate 20 million people against coronavirus by the end of 2020 - but only 4.2 million received a dose. Matthew Fox, a professor of global health epidemiology at Boston University in the US, explains why the country fell short of its target. (Image: Bottle labelled COVID-19 and a medical syringe shown in front of a USA flag, Credit: Reuters.)