CNN  —  As the US mulls over its future Covid-19 vaccination plan, data from three large health care systems indicate that even though a small percentage of people under age 65 have gotten the new Covid-19 booster, people this age are not becoming severely ill and overwhelming hospitals. “Even if they’re not getting boosted, young, healthy people are not getting super sick from this,” said Dr. Mangala Narasimhan, a senior vice president at Northwell Health, the largest health care provider in New York state. “We’re not seeing it. It’s not happening.” The US Food and Drug Administration has proposed a framework for annual Covid vaccinations for all Americans over the…