Active immunity is a type of immunity that occurs when the body produces its own antibodies in response to an antigen, such as a virus or bacteria. During an active immunity response, the body recognizes and remembers the antigen, allowing it to create specific antibodies to fight it off more quickly and effectively if it is encountered again.
Active immunity can be acquired in two ways: through natural means, such as being exposed to a virus or bacteria, or through artificial means, such as receiving a vaccine. When an antigen is encountered naturally, the body must first recognize it, and then activate B-cells to produce antibodies that will recognize and attach to the antigen, marking it for destruction by other immune cells. This process takes time, and so the body is vulnerable to the antigen during this period.
In contrast, when an antigen is encountered artificially, such as through a vaccine, the body is given the antigen in a weakened or inactive form. This allows the body to recognize it, and quickly begin producing the appropriate antibodies. This is why vaccines can be so effective at preventing diseases; the body has already created the antibodies it needs to fight off the virus or bacteria if it is ever encountered in the future.
In conclusion, active immunity is a type of immunity that is acquired when the body produces its own antibodies in response to an antigen. This can be done either naturally, through exposure to the antigen, or artificially, through the administration of a vaccine. Active immunity provides long-term protection against the antigen, as the body is able to quickly recognize and produce the necessary antibodies if the antigen is ever encountered in the future.
