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Vaccine Science: |
Vaccine Science
What is a Vaccine? How does it Work?A vaccine is a preparation given to an individual to create a state of protection against a disease. Most of us do not remember the first vaccination we received. A typical American receives his/her first vaccine at one week of age to protect against a number of childhood diseases. The deaths of thousands of U.S. children are prevented every year by timely vaccination. Unfortunately, vaccines are now taken for granted. Most Americans understand little about how vaccines work, how they are developed, or that we are on the verge of a new generation of vaccines that could be effective in diseases such as cancer or AIDS.
From its roots with a country doctor in local practice, vaccination has evolved into a highly specialized technology, with scientists from government, universities, and Indus trial research laboratories working in partnership to develop new, safer, and more effective agents to prevent the spread of infectious disease. An estimated 500 children die every year in the U.S. from diseases that could have been prevented by vaccination. Eradicating Disease: Vaccine Use WorldwideVaccines have been exceptionally effective against a number of diseases and have become one of the safest and most cost-effective weapons in medicine's arsenal against communicable disease. Perhaps no other intervention has had such a dramatic impact on the health and well-being of our society as the introduction of vaccines.
As testament to the power of vaccines, the story of smallpox is unparalleled. The carefully orchestrated use of smallpox vaccine by public health officials has led to the fulfillment of Jenner's prediction. There has been no smallpox in the world since 1977. The success in conquering smallpox led to the establishment of a new goal by public health officials around the world—the conquest of polio. At one time polio was a serious threat to the health of Americans. President Franklin Roosevelt was probably the most well known victim of polio. In the 1950's an intensive effort was under taken by researchers supported by the government, industry, and philanthropic organizations to develop a safe and effective vaccine for the disease. Urgency was so great that less than one month after the release for public use of the vaccine developed by Dr. Jonas Salk, 4,000,000 doses were subsequently given in the United States. Over the next four years, 450,000,000 doses of the vaccine were administered. Success in employing the polio vaccine has been so great that there has not been a new case of polio in the United States since 1975, and across the Western Hemisphere since 1991. The Next Generation of Vaccine DevelopmentExtraordinary advances in molecular biology and immunology have continued to create opportunities for enhancing the development of new vaccines. Newly emerging diseases, along with older diseases that have failed to yield to researchers, are posing unique challenges and have stimulated innovative approaches to the conquering of disease. AIDS vaccines. The Human Immunodeficiency Virus (HIV), the agent responsible for Acquired Immune Deficiency Syndrome (AIDS), continues to have a major impact on public health, not only in the U.S., but world wide. It is estimated that 5,000 people become infected with HIV daily. An affordable, safe, and effective vaccine is urgently needed as the most cost effective solution to treat and prevent the disease. To date more than 20 experimental AIDS vaccines have been studied in clinical trials world wide to determine their safety and ability to provoke an immune response. The infrastructure for research and evaluation of candidate vaccines has been carefully built up by the National Institute of Allergy and Infectious Diseases (NIAID) and relies upon the cooperation of the most dedicated government, academic, and industry scientists. This infrastructure contains:
Investigators in the National Cancer Institute (NCI) are contributing to the body of knowledge necessary to develop an AIDS vaccine. They have characterized mutations in the virus that permit escape of immunologic surveillance. Likewise, NCI scientists have characterized targets on the virus that evoke immune responses. The development of noninfectious virus particles, processed on a large-scale is being studied for use as vaccination material. NCI scientists are also studying the use of a class of naturally produced compounds that regulate immune responses, cytokines, to increase the response of the immune system to experimental vaccines. Barriers to the Research, Manufacture and Use of VaccinesAlthough vaccines have proven phenomenally successful in vanquishing death, disability, and disease, there are some barriers to more widespread immunization in the United States and worldwide. Obstructions are always encountered in the processes of discovery, research, and innovation. With regard to immunization, some gaps in technology jeopardize the use of existing vaccines, while others impede progress in the development of entirely new vaccines. All pose unique challenges to the biomedical research partnership of government, industry, and universities.
Likewise, a complete course of all the recommended child hood vaccines requires five separate visits to a health care provider. Consequently, many children, especially in remote locations, do not receive all of the required doses. Development of a "one-shot" immunization that combines several vaccines and is time-released would obviate the need for booster shots and greatly increase the number of children who receive a complete immunization regimen. This remains a challenge for the partners in discovery.
Research Priorities for Production of New and Improved Vaccines
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As a medical practice, vaccination to prevent certain infectious diseases has been employed for the last 200 years. Although precious little about the immune system was understood at that time, the English physician, Edward Jenner, made an observation that resulted in the first vaccination in 1796. Jenner observed that many milkmaids had contracted cowpox, a disease of cows that causes only mild illness in humans. Curiously, these women seldom contracted the much more severe and often fatal human disease, smallpox. To determine if there was any connection between the two diseases, he took some material from the cowpox lesion on the hand of a milkmaid. Jenner inoculated this into the skin of a young boy. Several weeks later Jenner again inoculated the boy, this time with infectious material containing deadly smallpox. The boy did not develop the disease and his protection was complete. This success led Jenner to predict that the final result of vaccination would be the "annihilation of smallpox."
Continued vigilance and coordinated use of vaccine has resulted in a trend of decreased incidence of polio worldwide. A recent resurgence of the disease, however, in such troubled regions as Chechnya, reminds us of the need to keep focused on the goal of eradicating polio by the year 2000. (Red=More than 10 cases; Yellow= 1-10 cases; Dark=0 cases)
For example, attempts to deliver vaccine to some of the most remote locations in the world demonstrate the continued reliance on a highly developed infrastructure and the limitations of current vaccine technologies. A number of vaccines must be kept at carefully controlled temperatures to remain effective. Constant temperature from the point of manufacture in the U.5. to vaccination sites in remote areas of the world is difficult.