The chickenpox vaccine is a shot that can protect nearly anyone who receives the vaccine from catching chickenpox. It's also called the varicella vaccine, because chickenpox is caused by the varicella-zoster virus. The vaccine is made from a live but weakened, or attenuated, virus.lthough the virus in the chickenpox vaccine is generally incapable of causing a disease, it still stimulates a response from the body's immune system. That response is what gives someone who's had a shot for chickenpox immunity or protection from the illness.