True Blood was an HBO horror/mystery/romance series based on the Sookie Stackhouse series of novels by Charlaine Harris.
The series as a whole follows Sookie Stackhouse starting shortly after the major world event of vampires “coming out of the coffin”. Where, after a Japanese company perfects the production of synthetic blood branded Tru Blood, vampires reveal themselves to be real and begin to integrate with mainstream society. Sookie has always had mind-reading abilities which has made it difficult to keep a human relationship, so she is immediately drawn to the vampires which she can’t mindread.
True Blood Season 6 ended with a world-changing event, the release of the bio-engineered Hepatitis V virus. Based on a mutation of the Hep-D virus, which only weakens a vampire for a time, Hep V is a much more contagious and much more deadly strain. Humans who contract the virus show no symptoms, but any vampire that drinks their blood will also catch the virus which causes extreme weakening and eventually the true death. It was originally spread using tainted Tru Blood so not only are vampires in danger from the virus, they also have lost their synthetic food source.