Category Archives: immunisation

Immunisation

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Definition:
Immunization, or immunisation, is the process by which an individual’s immune system becomes fortified against an agent (known as the immunogen).It  is the process whereby a person is made immune or resistant to an infectious disease.

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Immunization is done through various techniques, most commonly vaccination. Vaccines against microorganisms that cause diseases can prepare the body’s immune system, thus helping to fight or prevent an infection. The fact that mutations can cause cancer cells to produce proteins or other molecules that are known to the body forms the theoretical basis for therapeutic cancer vaccines. Other molecules can be used for immunization as well, for example in experimental vaccines against nicotine (NicVAX) or the hormone ghrelin in experiments to create an obesity vaccine.

Before the introduction of vaccines, the only way people became immune to an infectious disease was by actually getting the disease and surviving it. Smallpox (variola) was prevented in this way by inoculation, which produced a milder effect than the natural disease. It was introduced into England from Turkey by Lady Mary Wortley Montagu in 1721 and used by Zabdiel Boylston in Boston the same year. In 1798 Edward Jenner introduced inoculation with cowpox (smallpox vaccine), a much safer procedure. This procedure, referred to as vaccination, gradually replaced smallpox inoculation, now called variolation to distinguish it from vaccination. Until the 1880s vaccine/vaccination referred only to smallpox, but Louis Pasteur developed immunisation methods for chicken cholera and anthrax in animals and for human rabies, and suggested that the terms vaccine/vaccination should be extended to cover the new procedures. This can cause confusion if care is not taken to specify which vaccine is used e.g. measles vaccine or influenza vaccine.

When this system is exposed to molecules that are foreign to the body, called non-self, it will orchestrate an immune response, and it will also develop the ability to quickly respond to a subsequent encounter because of immunological memory. This is a function of the adaptive immune system. Therefore, by exposing an animal to an immunogen in a controlled way, its body can learn to protect itself: this is called active immunization.

The most important elements of the immune system that are improved by immunization are the T cells, B cells, and the antibodies B cells produce. Memory B cells and memory T cells are responsible for a swift response to a second encounter with a foreign molecule. Passive immunization is direct introduction of these elements into the body, instead of production of these elements by the body itself.

The most important elements of the immune system that are improved by immunization are the T cells, B cells, and the antibodies B cells produce. Memory B cells and memory T cells are responsible for a swift response to a second encounter with a foreign molecule. Passive immunization is direct introduction of these elements into the body, instead of production of these elements by the body itself.

Immunization is a proven tool for controlling and eliminating life-threatening infectious diseases and is estimated to avert between 2 and 3 million deaths each year. It is one of the most cost-effective health investments, with proven strategies that make it accessible to even the most hard-to-reach and vulnerable populations. It has clearly defined target groups; it can be delivered effectively through outreach activities; and vaccination does not require any major lifestyle change.

Immunizations are definitely less risky and an easier way to become immune to a particular disease than risking a milder form of the disease itself. They are important for both adults and children in that they can protect us from the many diseases out there. Through the use of immunizations, some infections and diseases have almost completely been eradicated throughout the United States and the World. One example is polio. Thanks to dedicated health care professionals and the parents of children who vaccinated on schedule, polio has been eliminated in the U.S. since 1979. Polio is still found in other parts of the world so certain people could still be at risk of getting it. This includes those people who have never had the vaccine, those who didn’t receive all doses of the vaccine, or those traveling to areas of the world where polio is still prevalent.

The Immunization can be achieved in an active or passive manner:
Vaccination is an active form of immunization.

Active immunization/vaccination has been named one of the “Ten Great Public Health Achievements in the 20th Century”.

Active immunization:.click & see
Active immunization can occur naturally when a person comes in contact with, for example, a microbe. The immune system will eventually create antibodies and other defenses against the microbe. The next time, the immune response against this microbe can be very efficient; this is the case in many of the childhood infections that a person only contracts once, but then is immune.

Artificial active immunization is where the microbe, or parts of it, are injected into the person before they are able to take it in naturally. If whole microbes are used, they are pre-treated.

The importance of immunization is so great that the American Centers for Disease Control and Prevention has named it one of the “Ten Great Public Health Achievements in the 20th Century”.  Live attenuated vaccines have decreased pathogenicity. Their effectiveness depends on the immune systems ability to replicate and elicits a response similar to natural infection. It is usually effective with a single dose. Examples of live, attenuated vaccines include measles, mumps, rubella, MMR, yellow fever, varicella, rotavirus, and influenza (LAIV).

Passive immunization:……...click & see
Passive immunization is where pre-synthesized elements of the immune system are transferred to a person so that the body does not need to produce these elements itself. Currently, antibodies can be used for passive immunization. This method of immunization begins to work very quickly, but it is short lasting, because the antibodies are naturally broken down, and if there are no B cells to produce more antibodies, they will disappear.

Passive immunization occurs physiologically, when antibodies are transferred from mother to fetus during pregnancy, to protect the fetus before and shortly after birth.

Artificial passive immunization is normally administered by injection and is used if there has been a recent outbreak of a particular disease or as an emergency treatment for toxicity, as in for tetanus. The antibodies can be produced in animals, called “serum therapy,” although there is a high chance of anaphylactic shock because of immunity against animal serum itself. Thus, humanized antibodies produced in vitro by cell culture are used instead if available.

Resources:
http://en.wikipedia.org/wiki/Immunization
http://www.who.int/topics/immunization/en/

Rotavirus Vaccine

Some Questions and Answers on Rotavirus Vaccine:

Why is it important to vaccinate against rotavirus? Isn’t the disease benign?
Rotavirus is the most common cause of severe gastroenteritis in infants and young children. The disease may cause severe dehydrating diarrhea with vomiting and fever. Almost all children are infected by age 5 years. Annually, rotavirus in the U.S. is responsible for 3 million infections, more than 400,000 physician visits, 160,000 emergency department visits, 55,000–70,000 hospitalizations, and between 20 and 60 deaths.

What are the recommendations for use of RotaTeq?
RotaTeq, the new rotavirus (RV) vaccine by Merck, is recommended for routine oral administration for all infants as a 3-dose series. The usual schedule is at ages 2, 4, and 6 months. The first dose may be given as early as age 6 weeks. The vaccine should not be administered to infants older than 32 weeks, even if the 3-dose series has not been completed. The first dose should be administered between ages 6 and 12 weeks. A minimum interval of 4 weeks should be observed between each of the doses.

Which infants should not receive RotaTeq?
The Vaccine should not be given to infants who has a severe allergic reaction to an RV vaccine component or following a prior dose, has altered immunocompetence, has a pre-existing chronic gastrointestinal disease or history of intussusception, or has a moderate or severe acute illness at the time of the clinic visit.

Can preterm infants receive RV?
ACIP recommends the vaccination of a preterm infant if the infant is at least age 6 weeks, is being or has been discharged from the hospital, and is clinically stable.

What is the evidence that RotaTeq will not be followed by intussusception?

The clinical trial that led to licensure of RotaTeq included more than 70,000 infants, and found no evidence of an increased risk of iintussusception in vaccine recipients

Source: kidsgrowth.com