DEAR DR. ROACH: My daughter got the Gardasil shot when she was 16 years old. Now there is a new, more effective vaccine Gardasil 9. Is it advisable to get another vaccine? Also, if a young girl has had sexual relations, is it too late to get the vaccine? D.J.
ANSWER: Gardasil is a brand of the vaccine for human papillomavirus, and is the only brand available in the U.S. at the time of this writing. The original Gardasil vaccine carried protection for four common strains of HPV, including the two most aggressive types (16 and 18).
In 2015, Gardasil 9 was released, which provides protection against nine different forms (again including 16 and 18). Revaccination with Gardasil 9 is not recommended for males or females who have completed any HPV vaccination.