An HIV vaccine showed modest results for the first time contradicting past thoughts that a vaccine for HIV was not possible, researchers found.

Infection in people who received a series of inoculations of a prime vaccine and booster vaccine was 31 percent less, compared to those receiving a placebo, CNN reports. The study was conducted among 16,000 Thai volunteers.

The vaccine is a combination of Sanofi-Aventis ALVAC canary pox vaccine and HIV vaccine AIDSVAX, made by VaxGen, Reuters reported.

Before this study it was thought vaccine for HIV is not possible, said Col. Jerome Kim who works as the HIV vaccines product manager for the U.S. Army, according to CNN.

These results were called the world's largest HIV vaccine trial ever. They mean an important first step to help researchers work for a more effective vaccine.

The National Institutes of Allergy and Infectious Diseases and the U.S. Army Medical Research and Materiel Command funded the study.

Medicine Infection