A new pill that directly targets hepatitis C for the first time was launched in the UK Wednesday, doctors announced. In clinical trials, adding \"Victrelis\" to standard therapy increased the number of chronic patients freed from the virus up to threefold. Hepatitis C is a blood-to-blood infection that attacks the liver. It is commonly spread by injecting drug users sharing needles, body piercing and tattoos. The virus can also be transmitted by blood transfusions, but donor screening has prevented this happening in the UK since 1991, the doctors added. Sexual transmission is extremely uncommon. The infection is known as the \"silent epidemic\" because it may take decades to produce any symptoms. Ultimately, the virus can cause serious liver damage or liver cancer. Around 216,000 people in the UK are believed to be chronically infected with hepatitis C but many do not know it. Until now, licensed treatments have relied on boosting the immune system to fight the infection. Victrelis, one of a class of drugs called protease inhibitors, is different because it attacks the virus directly. Charles Gore, chief executive of the The Hepatitis C Trust charity, said: \"Hepatitis C is called the silent epidemic because hundreds of thousands of people carry the virus yet the great majority has no idea they are infected. \"It can take decades for symptoms of hepatitis C to emerge and when they do, damage to the liver may have already occurred. Raising awareness of the condition and getting more people tested are critical, but we also need effective treatments once it is diagnosed. \"Current therapy can fail some patients, but the arrival of a new class of drugs will mean more people will be able to clear the virus.\"