Although COVID-19 vaccines work incredibly well for the vast majority of people, roughly 10 million Americans whose immune systems are compromised because of medication or disease may not be well protected. "This isn't over for us," said Michele Nadeem-Baker, who has chronic lymphocytic leukemia that's out of remission. She got two shots of the Moderna vaccine in March and April, but is pretty sure she has no protection against COVID-19. For Nadeem-Baker, a patient at Dana-Farber in Boston, the pandemic still looks a lot like it did during the worst of the outbreak: She always wears a mask, keeps her distances, avoids crowds. "It isn't easy to continue living like this," she said.