Two months after the first COVID-19 shots were administered, the race to vaccinate older Americans is gaining traction. More than half of states report that a third of people 65 and up have received their first dose. That’s according to an Associated Press analysis of data from 27 states. Some public health experts welcomed the news. They say it’s a positive sign that the system is working. But the effort is uneven. Many other states still lag behind on vaccinations of the higher-risk population. Older Americans have borne the brunt of the deaths and hospitalizations during the pandemic.