Vaccines and Immunology

Vaccination changes a patient's risk before exposure occurs. Instead of waiting for infection to generate immunity, a vaccine presents a carefully selected antigen so the adaptive immune system can prepare antibodies and immune memory without the target disease. That preparation is why a later exposure can be controlled more quickly and with less severe illness. Protection is not absolute, and immune responses may be weaker in older adults or people with immunocompromising conditions, but vaccination remains a major way to prevent complications and transmission. For the RN, the decision is not simply whether a vaccine is available. The patient’s age, medical risks, pregnancy status, immune function, previous doses, allergies, and the current provincial or territorial program determine which product is appropriate and whether it can be given safely.