1.2.2 Artificially acquired immunity
In artificially acquired immunity the person must be artificially and intentionally exposed to foreign antigens (actively), or given someone else’s antibodies (passively), in order to generate a protective immune response.
Artificially acquired active immunity
Artificially acquired active immunity is protection produced by intentional exposure of a person to antigens in a vaccine, so as to produce an active and lasting immune response. The antigens in the vaccine stimulate the immune system to produce antibodies and memory cells which are specifically directed against the antigens in the vaccine. After the immunization, if the living infectious agents with the same antigens that were in the vaccine get into the person’s body, the correct antibodies are already present and they bind to the infectious agents. The memory cells generate a rapid immune response from the rest of the immune system, and the infectious agents are quickly attacked and destroyed, often before symptoms of the disease can develop.
Vaccine doses
Some vaccines are given as a single dose, but others are given as a course of three doses at intervals of a few weeks. Some vaccines also require a ‘booster dose’ five to ten years after the original immunization. This is necessary to increase the immune response and ensure an adequate level of protection.
Once established, the protection provided by immunization usually lasts for several years, or even for life. This makes immunization a highly effective method of giving long-lasting immunity.
Artificially acquired passive immunity
Artificially acquired passive immunity is protection acquired by giving a person an injection or transfusion of antibodies made by someone else. These antibodies neutralise the infectious agents in the usual way, but the protection lasts only a few weeks because the antibodies gradually break down and are not replaced. In artificial passive immunization there is no involvement of the person’s own immune system.
1.2.1 Naturally acquired immunity