Innate immunity is a non-specific immunity that is present at birth. Innate immunity does not respond to specific antigens, but rather involves non-specific cellular and compliment responses. It also involves physical defenses like the skin and defense mechanisms like nasal secretions. The mother’s antibodies may linger in the baby for up to three months, but this is passive immunity, not innate immunity. Antigen-antibody responses including those that arise from immunizations are part of the acquired immune system.