Evaluation on the persistence of anti-HPV immune responses to the quadrivalent HPV vaccine in Chinese females and males: Up to 3.5 years of follow-up.

BACKGROUND: This was an extension study of a randomized, double-blind, placebo-controlled immunogenicity and safety study of the quadrivalent human papillomavirus (qHPV) (HPV 6, 11, 16, and 18) vaccine conducted in Chinese female subjects aged 9-45 years and male subjects aged 9-15 years. To investigate the persistence of anti-HPV 6, -11, -16, and -18 responses among Chinese subjects, subjects enrolled in the base study were followed up at around month 42 (approximately 3.5 years after vaccination).

METHODS: Among 600 subjects enrolled in the base study, a total of 468 subjects consented for participation in the extension study. Anti-HPV 6, -11, -16, and -18 antibodies were detected by the competitive Luminex immunoassay (cLIA) and total IgG Luminex immunoassay (IgG LIA).

RESULTS: Among the female subjects who received the qHPV vaccine, the proportions of subjects remained seropositive were high with both the cLIA and IgG LIA for HPV type 6, 11, and 16 through approximately 42 months following the first dose vaccination. For HPV 18, the seropositivity rate remained high as 82.0% with the IgG LIA, while it decreased to 53.6% with the cLIA, which was similar to the findings observed in other studies. The seropositivity rates remained high at month 42 for all qHPV types with both the cLIA and IgG LIA among the male subjects.

CONCLUSIONS: Administration of a 3-dose regimen of qHPV vaccine induces durable anti-HPV 6, anti-HPV 11, anti-HPV 16, and anti-HPV 18 responses among Chinese subjects for at least 3.5 years after vaccination. ClinicalTrials.gov registry:NCT01427777.