Magazine article UN Chronicle

AIDS Vaccines: The World's Best Hope to End the AIDS Epidemic

Magazine article UN Chronicle

AIDS Vaccines: The World's Best Hope to End the AIDS Epidemic

Article excerpt

TWENTY-FIVE YEARS AFTER ITS ONSET, AIDS continues to grow and outpace the global response. According to the Joint United Nations Programme on HIV/AIDS (UNAIDS) 2006 Report on the global AIDS epidemic, worldwide an estimated 38.6 million people are currently living with HIV. The epidemic is particularly worrisome for women and youth: in 2005, 59 per cent of infected people in sub-Saharan Africa were women; HIV-infected young women, aged 15 to 24, outnumbered their male counterparts by three to one. Approximately 6,000 to 7,000 people in that age group contract the virus each day.

The increasing effect of what is generally referred to as the feminization of HIV/AIDS is a phenomenon that can be observed in all regions across the world. Young people are also disproportionately affected, and despite internationally agreed goals to step up prevention efforts, activities to adequately protect them from HIV/AIDS are insufficient. However, there are signs of hope. Infection rates have plateaued in several African countries, but with around 4.1 million new infections annually, there is no room for complacency. The impact of HIV/AIDS is especially serious in the developing world since 95 per cent of new infections occur there. To help prevent HIV/AIDS, the need is evident for a vaccine--a substance that trains the immune system to recognize and protect against a disease or other infectious agent.

Historically, vaccines have been particularly efficient and cost-effective. The introduction of the smallpox vaccine, for example, made it possible to eradicate the disease altogether. They are also good poverty-fighting tools, as they tend to reach the poor and disadvantaged populations better than other health services.

On the minds of a lot of people, however, is the question, "Is it possible to develop an AIDS vaccine?" The answer is yes. Most scientists believe that an effective preventive AIDS vaccine is challenging but feasible. Virtually everybody's immune systems can keep the virus in check for a number of years. However, there are certain individuals that are resistant to HIV infection, such as a group of Kenyan sex workers who, despite repeated exposure to the virus, never contracted HIV. Their bodies somehow are able to control infection. It has also been found that AIDS vaccines can protect monkeys from the simian equivalent of HIV. All these are important, if not yet well understood, clues for the development of an AIDS vaccine. Accordingly, more than 30 vaccine candidates are currently undergoing early trials on four continents.

On the other hand, the challenges for developing an AIDS vaccine are formidable. Scientifically, the human immunodeficiency virus has turned out to be a very elusive target; in fact, HIV is one of the most complicated viruses ever identified, and it targets and destroys the very immune system that a vaccine traditionally triggers. Its genetic hyper-variability is daunting; millions of viruses are constantly produced and their mutation rates are staggering. The immune system is presented with an endless stream of new forms of the virus that it is unable to recognize and control.

In addition, clinical trials to test the safety and efficacy of an AIDS-vaccine candidate are long and costly. A vaccine is developed in laboratories and initially tested in animals, after which it generally has to go through three phases of testing on human beings to be licensed for use (see box below). In 2005, 13 new trials of preventive AIDS-vaccine candidates began in nine countries worldwide, including the developing world, two of them involving Phase II trials. India, China and Rwanda started their first vaccine trials in 2005 and South Africa began Phase II.

Contrary to a common myth that HIV vaccines can cause a person to get HIV or AIDS, it is absolutely not possible for the current HIV-vaccine candidates to cause a person to become infected with HIV, as these vaccines do not contain the virus, but rather only copies of small non-infective parts of the virus, so they cannot cause HIV transmission. …

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