The third season of HBO’s hit vampire series True Blood has just recently gotten started, but the numbers are impressive enough for those who make the decisions. It has been decided that a fourth season of the show is a worthy investment, and the green light has been given.

Speaking about the announcement, HBO president of programming Michael Lombardo said “The new season of True Blood is off to a terrific start, as enthusiasm for this unique show continues to build among both subscribers and critics. We’re looking forward to more chills from Alan Ball and his gifted team next year.” Series creator, executive producer, and sometimes writer/director Alan Ball also added “I am beyond thrilled to be able to continue working with this amazing cast and crew. This is the most fun I have ever had.”

True Blood is loosely based on The Southern Vampire Mysteries book series by Charlaine Harris. It takes place in a time when a synthetic blood has been created, bottled, and sold as Tru Blood, allowing for vampires to enter into society without a need to feed on humans anymore. The show follows Sookie Stackhouse (Anna Paquin) and 173-year old vampire Bill Compton (Stephen Moyer).

The 12-episode order for True Blood‘s fourth season will begin production at the beginning of next year, and just will debut in the summer of 2011.