Immunity Types. Minus Related Pages. Links with this icon indicate that you are leaving the CDC website. Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website. You will be subject to the destination website's privacy policy when you follow the link. Immunity is your body's ability to recognize germs to prevent them from causing illness.
The immune system's job is to help identify and eliminate dangerous germs that enter the body before they can cause disease or damage. There are two types of immunity: innate and adaptive. Innate immunity is the immune system that is present when you are born.
It is your body's first line of defense against germs. It includes physical barriers, such as skin and mucous membranes, and special cells and proteins that can recognize and kill germs. The problem with these special cells and proteins is that they can kill a germ, but once the germ is dead, the innate immune system forgets it. It does not communicate any information about the germ to the rest of the body. Without this information, the body cannot prepare itself to fight this germ if it should reinfect the body.
Adaptive immunity is protection that your body builds when it meets and remembers antigens, which is another name for germs and other foreign substances in the body. When your body recognizes antigens, it produces antibodies to fight the antigens. If the person encounters that pathogen again, long-lasting immune cells specific to it will already be primed to fight it.
The protection offered by passive immunization is short-lived, usually lasting only a few weeks or months. But it helps protect right away. Breast milk, though not as rich in protective components as colostrum, also contains antibodies that pass to the nursing infant.
This protection provided by the mother, however, is short-lived. During the first few months of life, maternal antibody levels in the infant fall, and protection fades by about six months of age. Artificial Passive immunity can be induced artificially when antibodies are given as a medication to a nonimmune individual.
These antibodies may come from the pooled and purified blood products of immune people or from non-human immune animals, such as horses. In fact, the earliest antibody-containing preparations used against infectious diseases came from horses, sheep, and rabbits.
Antibodies were first used to treat disease in the late 19 th century as the field of bacteriology was emerging. The first success story involved diphtheria, a dangerous disease that obstructs the throat and airway of those who contract it.
In , Shibasaburo Kitasato and Emil von Behring immunized guinea pigs against diphtheria with heat-treated blood products from animals that had recovered from the disease. The preparations contained antibodies to the diphtheria toxin that protected the guinea pigs if they were exposed soon thereafter to lethal doses of diphtheria bacteria and its toxin. Next, the scientists showed that they could cure diphtheria in an animal by injecting it with the blood products of an immunized animal.
They soon moved to testing the approach on humans and were able to show that blood products from immunized animals could treat diphtheria in humans.
The antibody-containing blood-derived substance was called diphtheria antitoxin, and public boards of health and commercial enterprises began producing and distributing it from onward.
Kitasato, von Behring, and other scientists then devoted their attention to treatment of tetanus, smallpox, and bubonic plague with antibody-containing blood products. The use of antibodies to treat specific diseases led to attempts to develop immunizations against the diseases.
Their pioneering work, along with advances in the separation of the antibody-containing blood component, led to many studies on the effectiveness of antibody preparations for immunization against measles and infectious hepatitis.
Before the polio vaccine was licensed, health officials had hopes for the use of gamma globulin an antibody-containing blood product to prevent the disease. William M. He showed that administration of gamma globulin containing known poliovirus antibodies could prevent cases of paralytic polio. However, the limited availability of gamma globulin, and the short-term protection it offered, meant that the treatment could not be used on a wide scale.
The licensure of the inactivated Salk polio vaccine in made reliance on gamma globulin for poliovirus immunization unnecessary. Today, patients may be treated with antibodies when they are ill with diphtheria or cytomegalovirus. Or, antibody treatment may be used as a preventive measure after exposure to a pathogen to try to stop illness from developing such as with respiratory syncytial virus [RSV], measles, tetanus, hepatitis A, hepatitis B, rabies, or chickenpox.
Antibody treatment may not be used for routine cases of these diseases, but it may be beneficial to high-risk individuals, such as people with immune system deficiencies. Vaccines typically need time weeks or months to produce protective immunity in an individual and may require several doses over a certain period of time to achieve optimum protection.
Passive immunization, however, has an advantage in that it is quick acting, producing an immune response within hours or days, faster than a vaccine. Additionally, passive immunization can override a deficient immune system, which is especially helpful in someone who does not respond to immunization.
Antibodies, however, have certain disadvantages. First, antibodies can be difficult and costly to produce. Although new techniques can help produce antibodies in the laboratory, in most cases antibodies to infectious diseases must be harvested from the blood of hundreds or thousands of human donors.
Or, they must be obtained from the blood of immune animals as with antibodies that neutralize snake venoms. In the case of antibodies harvested from animals, serious allergic reactions can develop in the recipient. Another disadvantage is that many antibody treatments must be given via intravenous injection, which is a more time-consuming and potentially complicated procedure than the injection of a vaccine.
Finally, the immunity conferred by passive immunization is short lived: it does not lead to the formation of long-lasting memory immune cells.
In certain cases, passive and active immunity may be used together. For example, a person bitten by a rabid animal might receive rabies antibodies passive immunization to create an immediate response and rabies vaccine active immunity to elicit a long-lasting response to this slowly reproducing virus. These antibodies have wide-ranging potential applications to infectious disease and other types of diseases. Monoclonal antibodies were first created by researchers Cesar Milstein, PhD , and Georges Kohler, PhD , who combined short-lived antibody-producing mouse spleen cells which had been exposed to a certain antigen with long-lived mouse tumor cells.
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Download PDF. Approved vaccine formulations Significant advances in cutting edge vaccine technologies over the past decade have resulted in two main types of SARS-CoV-2 vaccines now being approved for emergency use — an unprecedented achievement in modern medical science.
Triggering innate and adaptive responses To stimulate adaptive immunity, a vaccine requires a pathogen-specific immunogen as well as an adjuvant — the latter stimulates the innate immune system and provides the necessary second signal for T cell activation.
Full size image. Durability and future challenges Preclinical and early results from human trials show that both vaccines generate anti-S protein IgG and virus-specific neutralizing antibody responses for several months post-vaccination 5 , 6 , while the T cell data remain to be fully elucidated.
References 1. Article Google Scholar 9. Article Google Scholar Download references. Farber Authors John R. Teijaro View author publications. View author publications. Ethics declarations Competing interests The authors declare no competing interests.
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