A "vaccine" typically refers to a preventive vaccine. A preventive vaccine is designed for individuals who are not infected with the targeted disease, for example, HIV. The vaccine would either prevent the individual from becoming infected when exposed to the HIV virus, and, if infection does occur, stop the disease from progressing as quickly to AIDS. A therapeutic vaccine would be designed to reduce the impact of HIV/AIDS in individuals already infected with the disease.
A preventive vaccine works by teaching the immune system, before the body is exposed to a virus, how to defend against a virus by creating an immune response. If the vaccinated person is later exposed to the virus, the immune system responds quickly to neutralize and clear the virus.
The development of an effective HIV vaccine is complicated by several factors. First, HIV attacks the very immune system that a vaccine relies on to fight infections. Second, the virus mutates, making it especially difficult for the immune system to target it effectively. An additional challenge is that HIV inserts copies of its genetic material into cells of the immune system and other parts of the body, essentially hiding in the body for years. Eventually, the body loses its protective mechanisms and succumbs to AIDS.
Researchers worldwide have recognized that there are significant scientific obstacles to developing and delivering HIV vaccines, and that these obstacles can only be overcome through focussed and globally coordinated commitment and sustained long-term action.
In June 2004, the Global HIV Vaccine Enterprise was established with the support of the Bill & Melinda Gates Foundation and the United States National Institutes of Health. The Global Enterprise is an alliance of independent organizations, governments and stakeholders around the world dedicated to accelerating the development of preventive HIV vaccines by implementing a shared Scientific Strategic Plan (SSP); increasing and mobilizing significant new funding; and enhancing collaboration by promoting more efficient and faster ways for researchers to share successes and failures in order to avoid duplication of efforts. The SSP envisages implementation of a strategic plan for HIV vaccine research that spans vaccine discovery, product development and manufacturing, and clinical trials.
At the 2006 G8 Summit in St. Petersburg, Russia, the developed world leaders reaffirmed their commitment to the Island Summit Initiative, which signalled the creation of the Global Enterprise, noting that
"there is a need to enhance the scientific and technical capacities in this area at the global, regional and national levels." They also welcomed coordination of activities and cooperation between the Global Enterprise and other global initiatives and North/South partnerships active in this field. At the 2007 G8 Summit in Heilingendamm, Germany, the leaders reiterated their commitment to accelerating global HIV vaccine development efforts.
In February 2007, a collaborative initiative between the Government of Canada and the Bill and Melinda Gates Foundation was announced by the Prime Minister and Bill Gates.
In July 2010, at the XVIII International AIDS Conference in Vienna, Austria, the renewed Canadian HIV Vaccine Initiative was announced by Government of Canada in collaboration with the Bill and Melinda Gates Foundation.
Note: Some information on this page is courtesy of the International AIDS Vaccine Initiative (IAVI)
One of the greatest public health interventions in the past 100 years has been the discovery and widespread use of vaccines. More than 30 common infectious diseases are preventable with vaccines, and one of the most deadly, smallpox, was eliminated from human populations in 1979. The cost to eradicate smallpox was US$300 million, whereas the benefit has been estimated at US$27 billion over 20 years. Vaccines constitute one of the most cost-effective public health interventions available.
AIDS is a deadly disease that has already killed more than 30 million people worldwide. In the absence of a cure for AIDS, the development of vaccines to prevent HIV infection offers the greatest promise for slowing the epidemic.
Despite the fact that HIV infection is largely preventable, millions of new infections occur each year. The Joint United Nations Programme on HIV/AIDS (UNAIDS) (PDF document) and the World Health Organization (WHO) estimate that approximately 34 million people worldwide were living with HIV in 2010. An estimated 2.7 million people became newly infected with HIV in 2010.
The burden of HIV/AIDS (PDF document) is greatest in low-and middle-income countries (low-and-middle-income countries), particularly in sub-Saharan Africa, but also in the Caribbean, East Asia, Eastern Europe and Central Asia.
Sub-Saharan Africa remains the most heavily affected region, accounting for 71% of all new HIV infections in 2008. Over 90 percent of people living with HIV/AIDS are in the developing world. Women and children are especially vulnerable. An estimated 430,000 new HIV infections occurred among children under the age of 15 in 2008. Most of these new infections are believed to stem from transmission in utero, during delivery or post-partum as a result of breastfeeding. The number of children newly infected with HIV in 2008 was roughly 18% lower than in 2001, in part due to the success of programs to prevent the mother to child transmission of HIV. As well, women constitute about half of all people living with HIV - an estimated 15.7 million in 2008 - and more than 60% of new infections in Africa. Globally, AIDS is the leading cause of death for women of reproductive age.
The number of persons living with HIV (including AIDS), in Canada continues to rise, from an estimated 57,000 in 2005 to 65,000 in 2008 (a 14% increase). The increase in the number of people living with HIV is due to two factors: new treatments have improved survival of HIV-infected persons and new infections continue to occur. In terms of exposure category, men who have sex with men (MSM) continued to comprise the greatest proportion (44%) of new infections in 2008, which was only slightly lower than the estimated 45% they comprised in 2005. In 2008, the proportion of new infections among persons who inject drugs (IDU) was slightly higher than in 2005 (17% compared to 16%). The proportions of new infections were unchanged from 2005 in both heterosexual/ non-endemic (20%) and heterosexual/endemic (16%) exposure categories.
In terms of exposure category, men who have sex with men (MSM) continued to comprise the greatest proportion (44%) of new infections in 2008, which was only slightly lower than the estimated 45% they comprised in 2005. In 2008, the proportion of new infections among persons who inject drugs (IDU) was slightly higher than in 2005 (17% compared to 16%). The proportions of new infections were unchanged from 2005 in both heterosexual/ non-endemic (20%) and heterosexual/endemic (16%) exposure categories.
Ultimately, a safe, effective, affordable and globally accessible HIV vaccine is needed to end the AIDS epidemic and reverse its devastating social and economic impacts, particularly for those living in low-and-middle-income countries. Developing an HIV vaccine, however, is proving to be a challenging task.