A preventive medication targeted towards Human Immunodeficiency Virus (HIV) has been shown to be effective even when given to people who are at high risk of developing the disease, a new finding from a health insurer suggests.

The study, the findings of which now appear in the journal Clinical Infectious Diseases, was conducted by San Francisco-based health insurer Kaiser Permanente.

It involved over 600 individuals at high risk for HIV, mostly gay men, who at the time of enrollment were found healthy and were given pre-exposure prophylaxis (PrEP) pill, the blue pill Truvada, once a day.

For more than two years, none of the participants were found to be infected with HIV. In fact, some of the participants admitted to using fewer condoms and they also contracted sexually transmitted diseases, but none of them developed HIV.

The study was not a clinical trial, a method considered to be the most reliable way of testing the effectiveness of a treatment, but, experts say that the study results are promising.

"This is very reassuring data," said Dr. Jonathan E. Volk, lead author of the study and an epidemiologist for Kaiser Permanente, according to a report from The New York Times.

Nevertheless, more research is needed to establish the findings.

Truvada is an antiretroviral combination formulation composed of tenofovir and emtricitabine and developed by Gilead Sciences.

It was approved by the FDA in 2004 and since then it has been used to lower levels of HIV in the blood, controlling the symptoms and reducing the possibilities of transmitting HIV to other people.

In 2012, the U.S. Food and Drug Administration (FDA) approved the drug for reducing the risk of getting the virus and included it as part of PrEP. Since its approval, the Centers for Disease Control and Prevention recommended the use of the pill especially to those who are at high risk of getting HIV.