Risk Wise

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HIV/Aids Vaccine Research –

how many more false dawns?

Dr Muhammad Ali Dhansay, Vice-President, Research, South African Medical Research Council

IV remains a global health problem of unprecedented

dimensions. Unknown 25 years ago, HIV has already

caused an estimated 25 million deaths worldwide and

has generated profound demographic changes in the most

heavily affected countries. Sub-Saharan Africa remains the

region most heavily affected by HIV, accounting for 67 per cent

of all people living with HIV and for 75 per cent of Aids deaths

in 2007.

Globally, there were an estimated 33 million people living with HIV

in 2007. The annual number of new HIV infections declined from

three million in 2001 to 2.7 million in 2007. Overall, two million

people died due to Aids in 2007, compared with an estimated 1.7

million in 2001. Southern Africa continues to bear a dispropor-

tionate share of the global burden of HIV: 35 per cent of HIV

infections and 38 per cent of Aids deaths in 2007 occurred in that

sub-region.

Women account for half of all people living with HIV worldwide,

and nearly 60 per cent of HIV infections in sub-Saharan Africa. Young

people aged 15-24 account for an estimated 45 per cent of new HIV

infections worldwide. An estimated 370,000 children younger than

15 years became infected with HIV in 2007. Globally, the number of

children younger than 15 years living with HIV increased from 1.6

million in 2001 to two million in 2007. Almost 90 per cent live in

sub-Saharan Africa.

Sub-Saharan Africa’s epidemics vary significantly from

country to country in both scale and scope. Adult national

HIV prevalence is below two per cent in several countries

of west and central Africa, as well as in the horn of Africa,

but in 2007 it exceeded 15 per cent in seven southern

African countries (Botswana, Lesotho, Namibia, South

Africa, Swaziland, Zambia and Zimbabwe), and was above

five per cent in seven other countries, mostly in central

and east Africa (Cameroon, the Central African Republic,

Gabon, Malawi, Mozambique, Uganda and the United

Republic of Tanzania).

The estimated 5.7 million South Africans living with

HIV in 2007 make this the largest HIV epidemic in the

world. Meanwhile, the 26 per cent HIV prevalence found

in adults in Swaziland in 2006 is the highest prevalence

ever documented in a national population-based survey

anywhere in the world.

Despite increasing access to highly active antiretrovi-

ral therapy and community-based prevention initiatives,

over the past decade at least 40,000 Americans have

become HIV-infected each year. The Aids epidemic in

the US is increasingly affecting African Americans, who

comprise more than half of the new infections while

constituting less than 15 per cent of the US population.

The response

Since the start of the global response to the HIV

epidemic, prevention has been overshadowed by treat-

ment. “We cannot treat our way out of this pandemic.

For every two patients placed on antiretroviral drugs

during 2007, five new HIV infections occurred. A

renewed and revitalized movement for HIV prevention

is now required,” said an article in the Lancet. The reality

is that the pandemic will not be defeated without effec-

tive, multiple prevention strategies – biomedical,

behavioural, and structural interventions. The empha-

sis on prevention is an attempt to address the 2.5 million

new HIV infections every year, together with the long-

term consequences for children and communities. A safe

and effective HIV vaccine would be an enormously valu-

able tool in the campaign to stop the spread of HIV.

HIV vaccines

The development of an efficacious HIV vaccine is one

of the world’s greatest public health challenges. The

Scanning electron micrograph of HIV-1 budding

from a cultured lymphocyte

HIV has caused an estimated 25 million deaths worldwide

Source: Cynthia Goldsmith, Centers for Disease Control and Prevention