Washington (ECN) - This week marks a major event in Mexico City, as the world comes together for the International AIDS Conference.

The International AIDS Conference is set to spark unity all around the world, as the top researchers join to try to find an HIV vaccine.

Through the years, researchers have had a hard time coming up with a vaccine to prevent the virus, due to the fact that the HIV virus mutates year to year.

Over the past few years, the push for an HIV vaccine has gone by the wayside, due to the fact that there have been so many setbacks.

Good news was recently released though by the United Nations and World Health Organization.

They have stated that the number of people living with HIV in 2007 actually declined.

This was attributed to better prevention methods, among other things.  The hope is that the conference will renew the push towards a vaccine.