What is active immunity?
Active immunity is defined as immunity to a pathogen that occurs following exposure to the said pathogen.
When the body is exposed to a novel disease agent, B cells, a type of white blood cell, create antibodies that assist in destroying or neutralizing the disease agent. Antibodies are y-shaped proteins that are capable of binding to sites on toxins or pathogens called antigens.
Antibodies are disease-specific, meaning that each antibody protects the body from only one disease agent. For instance, antibodies produced when the body detects the virus that causes mumps will not provide any defense against cold or flu viruses.
When B cells encounter a pathogen, they create memory cells in addition to antibodies. Memory cells are a type of B cell produced following the primary infection that can recognize the pathogen. Memory cells can survive for decades, waiting within the body until the pathogen invades again.
When the body is exposed to the pathogen for a second time, the immune response is more robust, quickly addressing the disease agent.
Immunity does not happen immediately upon disease exposure. It can take days or weeks after the first exposure for active immunity to develop. But once it does so, the protection can last an entire lifetime.
Types of Active Immunity
Active immunity can occur in one of two ways: naturally or via immunization.
What Is Natural Immunity?
Your immune system defends your body against infections and illnesses. It makes proteins called antibodies that counteract or kill germs, like viruses and bacteria. You get protection, or “immunity,” from a specific disease when your immune system makes an antibody for it.
Natural immunity is created when a person becomes infected by a disease. Take, for instance, someone who becomes infected with chickenpox. After the initial infection, the body builds immunity against the disease. This natural active immunity is why people who catch chickenpox are immune for many decades against the disease.
How Long Does Natural Immunity Last?
Natural immunity to a disease can weaken over time, though. How quickly or slowly this happens depends on the disease.
For example, if someone gets natural immunity from a COVID-19 infection, the immunity may fade after 3 months. On the other hand, a child who gets measles is unlikely to ever catch it again.
Here’s a look at the different types of immunity, including the differences between natural and vaccine-induced immunity, and how they compare against COVID-19.
Artificial Active Immunity
Artificial active immunity is known as Vaccine-induced immunity, a person can build a resistance to disease following an immunization. An immunization is defined as the process by which someone becomes protected against a specific disease via the administration of a vaccine.
Vaccines use a weakened or dead form of a disease to stimulate an immune response. Vaccines are typically administered using an injection. However, there are vaccinations administered via the mouth or as a nasal spray.
When a person’s immune system detects the weakened or dead pathogen, it begins to take steps to destroy it. This includes forming new antibodies and memory cells specific to that pathogen. In the future, if the body is exposed to the said pathogen, antibodies will be created to protect the body.
Vaccination and immunity are essential for keeping large populations of people safe from infectious diseases. For instance, the flu vaccine prevents millions of people from becoming infected with the flu every year.