Everything Everything by Nicola Yoon
/Have you heard of the boy in the bubble? The boy who was allergic to everything, so allergic that he couldn’t even live outside; he had to live in a bubble where his air was filtered and he couldn’t touch anyone or anything. Rachel has SCID - severe combined immunodeficiency - which renders her defenseless against germs. As such, she's lived in her home her entire life, breathing filtered air, seeing only her mother and her nurse, and watching the world go by through her window. Her life starts to change, however, when a new family moves in next door. As Rachel watches them out her window, she becomes increasingly curious about Olly. He notices her watching and they start up an online friendship. Even though Rachel knows Olly’s secrets from spying on his family, she isn’t sure if she wants to tell him her secret.