Scientists in Trinity College Dublin (TCD) have begun work on a major new study aimed at assessing the effectiveness of a new hepatitis C vaccine.

The vaccine is aimed at preventing hepatitis C infection in people who are HIV positive. People with HIV have an increased risk of contracting hepatitis C, which is a blood-borne viral infection of the liver.

The main way it is spread is through direct contact with contaminated blood, such as via a blood transfusion or by sharing needles with an infected person. It can also be spread via unprotected sex and can be passed from a mother to her baby.

Of those who develop chronic hepatitis C, an estimated 30% will develop cirrhosis. Others will develop liver cancer, some of whom may require liver transplantation. Chronic hepatitis C is the most common reason for liver transplants in Europe.

Around 180 million people worldwide have hepatitis C, including between 20,000 and 50,000 people in Ireland. However, many of these are thought to be unaware they have the illness.

Currently, there is no effective vaccine for the infection and it is costly to treat - around €50,000 per patient. Treatment can take a long time, is not guaranteed to work and can result in side-effects.

"A safe, affordable and effective vaccine for hepatitis C would have a huge impact on combatting it given the multitude of people who are unaware of their diagnosis and represent a potential source for new infections," commented Dr Ciaran Bannan of TCD and St James's Hospital in Dublin.

According to the researchers, HIV-positive people are at an increased risk of contracting hepatitis C because of the similar ways in which both infections are acquired. Up to 30% of people with HIV are also infected with hepatitis C and it progresses more rapidly to liver damage in those with HIV.

The Trinity team is evaluating the ability and safety of a new vaccine, which aims to produce an immune response against hepatitis C. Studies by the University of Oxford involving healthy volunteers have produced positive results so far.

The TCD study is the first phase-1 vaccine study in HIV-infected people in Ireland. It will run for 20 months and will involve 20 patients in Dublin and Switzerland. Participants will be given two vaccines eight weeks apart. They will then be monitored closely.

The vaccines being tested are called AdCh3NSmut1 and MVA-NSmut and have been developed by ReiThera Srl and GlaxoSmithKline Biologicals SA. The research is led by Dr Bannan and Prof Colm Bergin of TCD.