why is it difficult to find the vaccine of AIDS and HIV viruses
Answers
Answer:
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Explanation:
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Since the epidemic emerged, 25 million people have died from AIDS and 60 million have been infected with HIV, according to the Joint United Nations Programme on HIV/AIDS. AIDS was detected in California and New York in 1981, first among gay men and drug users, then in hemophiliacs who had received blood transfusions, and later in non-drug-using men, women, and children.Initially, little was known about how AIDS was transmitted, and even less was known about the virus that caused it. In 1985, the virus itself was isolated. Following this discovery, Margaret Heckler, the US Human Services Secretary at that time, famously declared, "We hope to have a vaccine [against AIDS] ready for testing in about two years."Vaccines have worked well against once widespread diseases like smallpox and polio. After the AIDS virus was found, many people, including many scientists, thought AIDS would be added to the list. Vaccines mimic natural infections, during which the body produces antibodies that kill the virus. But unlike smallpox or polio, HIV doesn’t stimulate this kind of response – our immune systems are generally blind to the virus and unable to launch an effective antibody attack. Other challenges that scientists face as they try to create a vaccine include a lack of good animal models to study and the virus's ability to constantly change and mutate. Additionally, although controllers can keep levels of the virus low, no one has ever fully recovered from HIV infection. This means there's no natural, winning strategy for scientists to study and try to elicit.