Sunday is a very important day that will remind us of those fighting to find a solution for the Aids pandemic.

It is World Aids Vaccine Day.

According to UNAids there are an estimated 5,5million people living with HIV in South Africa. Most are aged between 15 and 50 and contribute to our economy.

Aids is devastating our country and a vaccine that could help stop its spread would be an incredibly powerful tool.

Today we acknowledge everyone who is helping to bring us closer to the reality of a vaccine.

There are thousands of volunteers, community advocates, supporters and researchers working around the clock to ensure that we develop an effective vaccine quickly.

Several months ago the second Aids vaccine to complete efficacy testing failed. It did not show protection against HIV infection, nor did it reduce the viral load of volunteers who later became infected.

We are grateful to the 800 trial volunteers. Though this trial was cut short, their efforts were not in vain. The lessons learnt will be used to design better vaccines, something that would not have been possible without these volunteers.

In the face of nearly 900 Aids-related deaths a day in South Africa, we must continue the quest for a tool that will protect our people from becoming infected.

In the wake of this news, scientists all over the world have been avidly discussing which way to head next in the search of a vaccine.

Many media accounts have misconstrued the conversations, describing researchers as if they have given up hope, when in fact they are rightly reappraising their approach. Scientists have a difficult task but there are sound scientific reasons to believe we can create a vaccine against Aids.

We have made significant progress in understanding the virus, advances that have set the research agenda for scientists around the world.

Today we know more about HIV than perhaps any other pathogen and have also made tremendous advances in developing drugs to treat people living with HIV-Aids.

Thanks to this progress, as well as to the enormous growth in programmes dedicated to providing access to these life-prolonging treatments, many HIV-infected South Africans live healthier and longer.

As we forge ahead with our search for an effective vaccine, we must continue to treat as many people as possible and encourage the use of existing prevention methods, such as condoms and male circumcision.

For every person who goes on anti-retroviral therapy nearly four others become HIV infected. So we must also focus on the long-term goal of developing a vaccine that will end the pandemic.

We discovered HIV 25 years ago and have only had a concerted vaccine effort for the last 10 years. South Africa must continue to play an important role in this endeavour. We have the scientific talent, research infrastructure and community support to make it happen.

l Dr Eftyhia Vardas is director of the HIV-Aids vaccine division and research laboratory at Chris Hani Bara and director of the Ndlela HIV research and clinical trials unit.