NEW YORK (AP) — The nation’s top public health agency is relaxing its COVID-19 guidelines and dropping the recommendation that Americans quarantine themselves if they come into close contact with an infected person. The Centers for Disease Control and Prevention also said Thursday that people no longer need to stay at least 6 feet away from others. The changes come more than 2 1/2 years after the start of the pandemic. They are driven by a recognition that an estimated 95% of Americans 16 and older have acquired some level of immunity, either from being vaccinated or infected.