What type of immunity is acquired when a baby receives a Hep-B vaccine?

The correct answer pertains to active immunity. When a baby receives a Hepatitis B (Hep-B) vaccine, the vaccine stimulates the immune system to produce its own antibodies against the virus. This process involves the introduction of an inactivated or weakened form of the virus or parts of the virus, prompting the immune system to generate a response. The baby's body develops memory cells that will help recognize and fight off the virus if exposed in the future.

Active immunity provides long-lasting protection, as it involves the body actively engaging with the antigen and building an immune response. This is different from passive immunity, where antibodies are directly transferred from one individual to another (such as from mother to baby through breast milk) without the baby's immune system being activated.

Naturally acquired immunity occurs through natural exposure to pathogens, while artificially acquired immunity involves vaccinations, which is a broader category that includes the active immunity received from the Hep-B vaccine. In this context, specifying that active immunity is the result of the vaccine is key to understanding how the immune system responds and is fortified against future infections.