VACCINATION

Life-cycle of an Immunization Program



1)When there is no vaccine for a disease, the number of people getting the disease is usually high. People are worried about the disease and its effects.
2)When an immunization program for a disease begins, the number of people being vaccinated rises.
3)At the same time, there will be some adverse reactions associated with the vaccine –almost always very few and very mild compared with illness and complications associated with the disease.
4)As the number of people being vaccinated rises, the number of cases of disease drops. Eventually, the number of people getting the disease may approach the small number of people having adverse reactions. (This number remains fairly constant because it is a percentage of the number of people being vaccinated.).
5)At this point, most people may never have experienced the disease, and their attention turns from worry about the disease to concern about possible side-effects of the vaccine. People may start to question whether the vaccine is necessary or safe, and some people will stop getting immunized.
6)If enough people stop getting immunized, disease numbers will start to rise again, and there will be outbreaks.
7)People are reminded of how bad the disease can be, and turn back to immunization to avoid it. Vaccinations increase once more and disease declines.
8)Ultimately, we hope that enough people get immunized that the disease disappears 9)altogether. (So far this has happened only with smallpox, but it could happen with other diseases, such as polio and measles, in the not-too-distant future.)
When there is no more disease, the immunization program can be stopped. The numbers of vaccinations and adverse reactions drop to zero.
Immunity Types
aACTIVE IMMUNITY

Active immunity results when exposure to a disease organism triggers the immune system to produce antibodies to that disease. Exposure to the disease organism can occur through infection with the actual disease (resulting in natural immunity), or introduction of a killed or weakened form of the disease organism through vaccination (vaccine-induced immunity). Either way, if an immune person comes into contact with that disease in the future, their immune system will recognize it and immediately produce the antibodies needed to fight it.
Active immunity is long-lasting, and sometimes life-long.

b PASSIVE IMMUNITY

Passive immunity is provided when a person is given antibodies to a disease rather than producing them through his or her own immune system.
A newborn baby acquires passive immunity from its mother through the placenta. A person can also get passive immunity through antibody-containing blood products such as immune globulin, which may be given when immediate protection from a specific disease is needed. This is the major advantage to passive immunity; protection is immediate, whereas active immunity takes time (usually several weeks) to develop.
However, passive immunity lasts only for a few weeks or months. Only active immunity is long-lasting

How Do Vaccines Protect Children from Diseases?
Each child is born with a full immune system composed of cells, glands, organs, and fluids that are located throughout his or her body to fight invading bacteria and viruses. The immune system recognizes germs that enter the body as "foreign" invaders, or antigens, and produces protein substances called antibodies to fight them. A normal, healthy immune system has the ability to produce millions of these antibodies to defend against thousands of attacks every day, doing it so naturally that people are not even aware they are being attacked and defended so often (Whitney, 1990). Many antibodies disappear once they have destroyed the invading antigens, but the cells involved in antibody production remain and become "memory cells." Memory cells remember the original antigen and then defend against it when the antigen attempts to re-infect a person, even after many decades. This protection is called immunity.
Vaccines contain the same antigens or parts of antigens that cause diseases, but the antigens in vaccines are either killed or greatly weakened. When they are injected into fatty tissue or muscle, vaccine antigens are not strong enough to produce the symptoms and signs of the disease but are strong enough for the immune system to produce antibodies against them (Tortora and Anagnostakos, 1981). The memory cells that remain prevent re-infection when they encounter that disease in the future. Thus, through vaccination, children develop immunity without suffering from the actual diseases that

How Vaccines Prevent Disease

Disease prevention is the key to public health. It is always better to prevent a disease than to treat it. Vaccines prevent disease in the people who receive them and protect those who come into contact with unvaccinated individuals. Vaccines help prevent infectious diseases and save lives. Vaccines are responsible for the control of many infectious diseases that were once common in this country, including polio, measles, diphtheria, pertussis (whooping cough), rubella (German measles), mumps, tetanus, and Haemophilus influenzae type b (Hib).
Parents are constantly concerned about the health and safety of their children and take many steps to protect them. These steps range from child-proof door latches to child safety seats. In the same way, vaccines work to protect infants, children, and adults from illnesses and death caused by infectious diseases. While the US currently has record, or near record, low cases of vaccine-preventable diseases, the viruses and bacteria that cause them still exist. Even diseases that have been eliminated in this country, such as polio, are only a plane ride away. Polio, and other infectious diseases, can be passed on to people who are not protected by vaccines.
Vaccine-preventable diseases have a costly impact, resulting in doctor's visits, hospitalizations, and premature deaths. Sick children can also cause parents to lose time from work