Question

How can an active immunity be obtained?

Answer 1

Adaptive immunity, also known as acquired immunity, is the third line of defence. Adaptive immunity protects the body from a specific pathogen. Adaptive immunity is further broken down into two sub-groups: active immunity and passive immunity.

Complete answer:
Active immunity is defined as immunity to a pathogen that occurs after exposure to the pathogen. When the body is exposed to a novel disease agent, B cells, a type of white blood cell, develop antibodies that help to destroy or neutralise the disease agent. Antibodies are y-shaped proteins that can bind to toxins or pathogens called antigens.

Antibodies are disease-specific, meaning that every antibody protects the body from just one disease agent. For example, antibodies produced when the body detects a virus that causes mumps will not provide any defence against cold or flu viruses.

In addition to antibodies, when B cells encounter a pathogen, they create memory cells. Memory cells are a type of B cell produced after a primary infection that can recognise the pathogen. Memory cells can survive for decades, waiting for the pathogen to invade the body again.

When the body is exposed to the pathogen for a second time, the immune response is more robust and the disease agent is quickly addressed. Immunity does not occur immediately after exposure to the disease. The development of active immunity may take days or weeks after the first exposure. But once it does, protection can last a lifetime.

Active immunity can occur in one of two ways: natural or through immunization.
Natural immunity:
Natural immunity is created when a person becomes infected with a disease. Take, for example, someone who is infected with chickenpox. After the initial infection, the body builds immunity from the disease. This natural active immunity is why people who catch chicken pox have been immune to the disease for many decades.

Vaccine-induced Immunity:
Also known as artificial active immunity, a person may develop resistance to a disease following immunisation. Immunization is defined as the process by which a person is protected against a specific disease through the administration of a vaccine.

Vaccines use a weakened or dead disease to stimulate an immune response. Vaccines are usually administered by injection. Vaccinations are however administered via the mouth or as a nasal spray.

Note: When a person's immune system detects a weakened or dead pathogen, steps begin to be taken to destroy it. This includes the formation of new antibodies and memory cells specific to the pathogen. In the future, if the body is exposed to the pathogen, antibodies will be created to protect the body. Vaccination and immunity are essential for keeping large populations safe from infectious diseases.