Immunogenicity of Human Papillomavirus Virus Vaccine in a High-risk and Understudied Group: Female Sex Workers

BACKGROUND: Female sex workers (FSW) have multiple sexual partners and are at higher risk of human papillomavirus virus (HPV) infection. They could be a target group for HPV vaccination, but their expected immune response to the HPV vaccine is unclear due to potential exposure to the virus. METHODS: We conducted a pilot study (NCT04590521) in Hai Phong, Vietnam to evaluate HPV vaccine immunogenicity among FSW aged 18-26 years. All participants received the standard 3-dose schedule (0, 2, and 6 months) of the quadrivalent Gardasil vaccine (4vHPV). Cervical swabs were collected at time of vaccination to detect high-risk HPV DNA and cervical abnormalities. Blood samples were collected at baseline and at 2, 3, 6, and 7 months after the first dose to determine neutralizing antibody (nAb) responses to HPV16 and HPV18, as well as related HPV52 and HPV58. RESULTS: A total of 63 FSW with a median age of 23.4 years (IQR, 21.6-25.4 years) were recruited. Prevalence of any high-risk HPV type and HPV16/18 infection at baseline was 28.6% (18/63) and 9.5% (6/63), respectively. Following the first dose, 90% and 55% of individuals were seropositive for HPV16 and HPV18, respectively. By month 7, all participants were seropositive to both HPV16 and HPV18. Higher nAb responses were observed among HPV-DNA-negative participants at baseline compared with HPV-DNA-positive participants after 2 and 3 doses (HPV16, geometric mean ratio [GMR] 2.97 and 1.63, P < .05; HPV18, GMR 2.83 and 1.49, P = .06). CONCLUSIONS: Three doses of 4vHPV elicited robust nAb to HPV16 and HPV18 among FSW. Further studies are needed to evaluate the effectiveness of HPV vaccination in FSW. Clinical Trials Registration.NCT04590521.