Which of the following is NOT an example of active immunity?

Active immunity occurs when the immune system is stimulated to produce its own antibodies in response to an infectious agent or via vaccination. This type of immunity usually develops after direct exposure to the pathogen or through vaccination and provides long-lasting protection.

Pneumococcal conjugate vaccine, hepatitis A immunization, and influenza virus immunization all function by introducing an antigen to the immune system, prompting it to generate an immune response and build memory against these pathogens. Therefore, these vaccines are examples of active immunity, as they induce the body’s immune system to produce antibodies.

On the other hand, hepatitis B immune globulin (HBIG) is considered a form of passive immunity. This is because it provides immediate, but temporary, immunity through the administration of pre-formed antibodies collected from individuals who have recovered from or been vaccinated against hepatitis B. Unlike active immunity, passive immunity does not require the body to generate its own immune response and does not provide lasting protection, as it lasts only for a short duration until the body eventually degrades those antibodies. This distinction highlights why this option is not classified as active immunity.