Immunogenicity of HPV Vaccine in a High-Risk and Understudied Group: Female Sex Workers.

Abstract

Female sex workers (FSW) have multiple sexual partners and are at higher risk of 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. 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 three-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 post-first dose to determine neutralising antibody (NAb) responses to HPV16 and 18, as well as related HPV52 and HPV58. A total of 63 FSW with a median age of 23.4 years (IQR 21.6-25.4) 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 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: GMR: 2.97 and 1.63, p<0.05; HPV18: 2.83 and 1.49, p=0.06). 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.