Harnessing the immune system to treat chronic infectious diseases or cancer. Injecting antigens (active immunization) or serum or serum fractions (passive immunization) into the body to create artificial immunity in humans and animals. The most common form is active immunization. It is usually a series of injections, inhalations or oral doses of preparations obtained from micro-organisms or their metabolic products. The series of two or more injections produce immunizations for a year or more through the formation of specific antibodies (specialized immune cells that recognize specific proteins) and immune cells and through stimulating non-specific immunity factors. Passive immunization is produced by injecting a preparation containing pre-formed antibodies, which neutralise toxins, inactivate the causative agent, and prevent the agent from spreading. Passive immunization creates immunity for periods of up to a month. It is used to prevent the spread of disease or to mitigate its course.
Each year, 2 million children die from vaccine-preventable disease.
Poliomyelitis, tetanus, measles, whooping cough, diphtheria and tuberculosis still kill more than eight million children each year. In 1974, only 5 percent of children in developing countries were immunized against these diseases. Fifteen years ago, the benefits of immunization were restricted to no more than 15 percent of the developing world's population. In 1994, as a result of the efforts of UNICEF and WHO, there is an 80 percent immunization rate, saving the lives of more than 3 million children each year at a cost of about US$1,400 million, as well as half a million cases of polio each year. It is proposed to increase the coverage of this Expanded Programme of Immunization (EPI) to 95 percent coverage of the world's children. Expansion would have significant impact on children in poor households, who make up a disproportionately large share of those not yet reached by the EPI. Other vaccines, particularly those for hepatitis B and yellow fever, could be added to the six currently included in the EPI, as could vitamin A and iodine supplements. In most developing countries such an "EPI Plus" cluster of interventions in the first year of live would have the highest cost-effectiveness of any health measure available in the world today. Countries that have seen a substantial rise in tetanus vaccinations from 1990 to 1992 include inter alia: Guinea (60 percent rise); Sri Lanka (25 percent rise); Viet Nam (24 percent rise); the Philippines (22 percent rise). In Somalia, during a successful immunization campaign, 700,000 children (nearly 50 percent of the total under-five population) received one dose of measles vaccine and were given vitamin A supplements.
The children's vaccine initiative (CVI) is a broad-based coalition of organizations, distinguished research scientists, and UNICEF's commitment to improve children's health through the development and sustainable delivery of existing and new vaccines. In 1993, a CVI task force sponsored teams of experts to visit Bangladesh, Egypt, India, Indonesia, Iran, Mexico, Pakistan, the Philippines, South Africa and Viet Nam to develop national vaccine supply plans, assess local production capacity and evaluate quality control.
A 2003 survey of parents of 21,000 children in the USA found that overall, 75% got their full quota of vaccines against eight childhood diseases – diphtheria, measles, mumps, whooping cough, polio, rubella, tetanus and Haemophilus influenzae diseases. This compares to 73.7% in 2001 and levels below 70% in the 1960s. Gaps in coverage remained with southwestern and northwestern states with the worst record. One problem is that parents have trouble keeping track of all the vaccines their children need, but a small movement of parents who question the value of vaccines is also having an impact, experts have found. While schools require children to be fully vaccinated for enrollment, states allow parents to opt out for religious reasons and, increasingly, because of "philosophical" opposition.
Along with nutrition and sanitation, immunization can eliminate 90 percent of preventable deaths in under-developed countries.
Immunizations result in a small percentage of deaths. It is necessary to weigh the risk of the immunization against the risk of the disease.
Introducing foreign agents into the body is unnatural; for this reason it is opposed by some religious groups.
Vaccination does not account for the impressive declines in mortality seen in the first half of the 20th Century. Nearly 90% of the decline in infectious disease mortality among US children occurred before 1940, when few antibiotics or vaccine were available.