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Sample essay topic, essay writing: Vaccine Testing - 1082 words
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Michelle RaessThe Human BodyDr. Shirley M. BartidoHIV Vaccine Testing in Africa The United Nations estimates that 5.8 million people per year become infected with the immunodeficiency virus (HIV). Ninety percent of these infections occur in sub- Saharan Africa, where infected persons do not have access to antiviral therapy. Approximately 2.4 million Africans died of AIDS in 2002, and 3.5 million occurred in the region. Where in the United States $12,000-$15,000 is usually spent on treating an HIV-infected person per year, only $6 is spent annually per person in Uganda.
The only method presently available to prevent the spread of HIV in less-developed countries is counseling against the behaviors that increase the risk of infection. It's obvious that a vaccine would be more beneficial to these countries. There are several HIV vaccines in various stages of development that need to be tested to see their effectiveness. It seems reasonable to carry out such trials in less-developed countries. Since 1984, when HIV was identified as the cause of AIDS, the development of a HIV vaccine has been a goal for the science world
Researchers have many different strategies that may lead to an effective HIV vaccine. Scientists take small parts of the HIV virus and change them in a laboratory to create synthetic copies. The experimental vaccines do not use whole or live HIV. The vaccines cannot cause HIV or AIDS. The vaccines being tested should produce either antibodies or cytotoxic T cells to fight the infection.
There are several types of experimental HIV vaccines. A peptide vaccine is made of tiny pieces of proteins from the HIV virus. The recombinant subunit protein vaccine is made of bigger pieces of proteins from the HIV virus. Examples of a recombinant subunit protein are gp120, gp140, or gp160 produced by genetic engineering. The DNA vaccine uses copies of a small number of HIV genes which are inserted into pieces of DNA called plasmids.
The HIV genes will produce proteins very similar to the ones from real HIV. A live vector vaccine is made of HIV genes that have been taken out of the virus and altered. The genes are inserted into another vector, which carries them into the body's cells. The genes in turn produce proteins that are normally found on the surface of the HIV virus. This type of vaccine most resembles the HIV virus but isn't harmful. Many vaccines that are used today, like the smallpox vaccine, use this method. A vaccine combination uses any two vaccines, one after another, to create a stronger immune response. It's often referred to as "prime-boost strategy." Lastly, a virus-like vaccine (pseudovirion vaccine) is a non-infectious HIV look-alike that has one or more, but not all HIV proteins.
Although there are several types of HIV vaccines, scientists are still learning about how the vaccines might work to prevent HIV infection. An HIV vaccine may be totally successful in preventing infection, known as "sterilizing immunity." Sterilizing immunity may be possible in 100% of the population, or maybe only in certain groups. In another scenario, a preventive vaccine may not prevent primary infection, but decrease the possibility of HIV transmission from an infected person to another person. Yet another possibility is that a vaccine may slow the process of infection, so that even if a person becomes HIV infected, the vaccine helps the vaccinated individual remain healthier longer. After an experimental vaccine has been tested in laboratory and animal studies to determine its safety and immune response, it must successfully complete three stages of testing in people before it can be licensed. The three stages of Vaccine Testing in Humans are:I.) 20-100 participants; Primary Rationale- safetyII.) Hundreds of participants; Primary Rationale- safety & immunogenicityIII.) Thousands of participants; Primary Rationale- safety & effectivenessA Phase I trial is the first setting where an experimental HIV vaccine is given to people.
The trial would include about 20-100 HIV-negative volunteers. This trial primarily seeks information on safety, looking for any vaccine-related side effects. This is done by comparing the vaccine with a control. A Phase I trial can also provide initial data on the dose and the time between vaccinations that achieve the optimal immune response. Scientists may be able to analyze results to determine if the vaccine will have an effect against variations of HIV found around the world.
A Phase I trial typically lasts 12 to 18 months.Once Phase I trials show the experimental HIV vaccine to be safe, it goes on to Phase II trials for more safety testing. Phase II trials involve hundreds of people. These trials still focus on safety, but researchers gather more information about the human immune response and more data on the most effective dose and timing. A Phase II trial can last two to three years.The most promising experimental vaccines then move to Phase III trials. These trials involve thousands of people HIV-negative volunteers.
Phase III trials are designed to answer the question of whether or not a vaccine is effective in preventing HIV infection. Phase III data showing a vaccine's safety and effectiveness in large numbers of people is required to support a licensure application to the Food and Drug Administration (FDA). A Phase III trial can take three to five years to complete.Experimental vaccines used in all phases of testing are not produced from live virus or from HIV-infected human cells. Volunteers cannot get HIV infection or AIDS by receiving an experimental vaccine.In conclusion, it's been 20 years since the first evidence of Acquired Immune Deficiency Syndrome (AIDS) and the discovery of the virus that causes this syndrome, the Human Immunodeficiency Virus (HIV). Since then, over 60 million people have become infected, 40 million of whom are currently living with HIV - 70% of them in Africa.
Southern Africa is the worst affected region with South Africa, Zimbabwe and Botswana reporting infection rates of over 25% of women attending antenatal clinics in the public health services. South Africa is not the only African country involved in HIV vaccine trials. Uganda and Kenya have already started Phase I clinical trials of other candidate vaccines. In South Africa, extensive preparation work is being undertaken in readiness for Phase I trials. It is expected that several candidate vaccines will be tested in South Africa in the next few years.References CitedI.) Sylvia S.
Mader Human Biology: Eighth EditionII.) Lynellyn D. Long and E. Maxine Ankrah Women's Experiences with HIV/AIDS: An International PerspectiveIII.) Alexander Irwin, Joyce Millen and Dorothy Fallows Global AIDS: Myths and FactsIV.) WWW.WHO.ORGV.) WWW.CDC.GOVVI.) WWW.NIH.GOVVII.) WWW.UNAIDS.ORG.
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