Canadian HIV Vaccine Initiative

HIV Vaccine

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 25 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) and the World Health Organization (WHO) estimate that approximately 33.2 million people worldwide were living with HIV in 2007 – 4.2 million more than in 2001. An estimated 2.5 million people became newly infected with HIV in 2007.

The burden of HIV/AIDS is greatest in low- and middle-income countries (LMICs), particularly in sub-Saharan Africa (http://www.acdi-cida.gc.ca/CIDAWEB/acdicida.nsf/En/NIC-55134013-NQU ), but also in the Caribbean, East Asia, Eastern Europe and Central Asia. Over 90 percent of people living with HIV/AIDS are in the developing world. Young people (15 to 24 years of age) account for about 40 per cent of new HIV infections each year, and each day, 1,200 children worldwide become infected with HIV. As well, women constituted an estimated 15.4 million of all people living with HIV in 2007 and almost 50 percent of all new infections.

The number of persons living with HIV in Canada is also increasing. The Public Health Agency of Canada estimates that 58,000 people were living with HIV infection in Canada at the end of 2005 – a 16 per cent increase from the 2002 estimate of 50,000. An estimated 27 per cent of these individuals – 15,800 people – were believed to be unaware of their infection and thus were not seeking treatment and may have been unknowingly infecting others.

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 LMICs. Developing an HIV vaccine, however, is proving to be a challenging task.

Developing an HIV Vaccine

A "vaccine" typically refers to 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.

Significant work has been undertaken in Canada and around the world to develop an effective HIV vaccine, but none has yet been proven to stimulate immune responses that are sufficient to protect against infection. 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.

Canada has significant expertise in vaccine development and could contribute significantly to global efforts. A Memorandum of Understanding (MOU) between the Government of Canada and the Bill & Melinda Gates Foundation was announced by the Prime Minister and Bill Gates in February 2007. The CHVI implements the MOU and represents Canada’s contribution to the Global Enterprise. It also strengthens Canada’s role in promoting global security, human health and development, particularly in LMICs.

Note: Some information on this page is courtesy of the International AIDS Vaccine Initiative .