Human Immunodeficiency Virus (HIV) prevention pill Truvada by Gilead proved to be more effective than initially thought, based on two real-world studies.

While the once-a-day prevention pill may have shown promise in tightly controlled clinical trials, some experts are still not convinced of its effectiveness when used in the real-world settings.

Despite that, real-world studies have proven that the drug actually works.

The first trial was conducted by San Francisco-based insurer Kaiser Permanente Medical Center, which appeared in the journal Clinical Infectious Diseases, and it showed evidence that the pill works in preventing HIV infections.

Truvada was given to more than 600 individuals, mostly men who had sex with men. The results showed that although these patients contracted different kinds of sexually transmitted diseases, none of them developed HIV for over two years.

The results from this study suggested a 100 percent success rate for the pill.

Another separate trial, conducted by researchers from the Medical Research Council Clinical Trials Unit (MRC CTU) of University College London, together with the Public Health England, involved 545 participants from 13 sexual health clinics in England, as stated in University College London's release.

The study, dubbed as PROUD (Pre-exposure Option for reducing HIV in the UK: immediate or Deferred), was published in The Lancet on Sept. 9 and it showed that the risk of HIV infection is reduced by 86 percent.

Researchers of the PROUD study concluded that their research findings provide strong evidence that pre-exposure prophylaxis (PrEP) should be included as an additional treatment to the standard HIV prevention regimen.

Truvada is already available in the United States and now, the National Health Science (NHS) is considering offering the drug for free to high-risk individuals in the United Kingdom, The Independent reported.

NHS is expected to make a decision by early next year, but the studies conducted by independent experts showed that prescribing PrEP drugs would help NHS save money in the long run as cases of HIV infections are expected to drop and the cost to treat them will also be reduced.