As a result of continuous mutations and recombinations Hepatitis B Virus has evolved, much like Influenza A Virus, into several genotypes. Eight genotypes of Hepatitis B Virus (A-H) are currently recognized, and subgenotypes have recently been described in four of these genotypes (A, B, C and F). The genotypes show a distinct geographical distribution between and even within regions.
In 2008, several reports[2,3] were published that a possible new genotype was circulating in Southeast Asian countries, such as Vietnam and Laos. Research indicated that Hepatitis B, genotype I was the result of a complex recombination pattern, suggesting it was formed outside of Southeast Asia before spreading within Laos and Vietnam, and giving birth to a new genotype with subgenotypes, which later recombined with regional strains.
This certainly shows that Hepatitis B Virus is constantly evolving, recombining and mutating and it’s only a question of time before the existing vaccines will not protect us anymore.
 Kramvis et al: Hepatitis B virus genotypes in Vaccine - 2005
 Tran et al: New complex recombinant genotype of hepatitis B virus identified in Vietnam in Journal of Virology - 2008
 Olinger et al: Possible New Hepatitis B Virus Genotype, Southeast Asia in Emerging Infectious Diseases - 2008