Poster Presentation Lorne Infection and Immunity 2022

Antibody profiles 6 years following reduced-dose quadrivalent HPV vaccine schedules in adolescent Fijian girls (#198)

Chau Quang 1 , Zheng Quan (Ryan) Toh 1 , Paul V Licciardi 1 , Amy W Chung 2
  1. Murdoch Children's Research Institute, Melbourne, VIC, Australia
  2. Department of Microbiology and Immunology, Peter Doherty for Infection and Immunity, Melbourne, VIC, Australia

Persistent infection with human papillomaviruses (HPV) can cause cervical cancer, which is the fourth most common cancer in women worldwide. Most cases occur in low- and middle-income countries (LMIC) where resource constraints pose significant barriers to prevention. Prophylactic HPV vaccines have demonstrated strong protection against persistent HPV infection, cervical pre-cancerous lesions and cancer. These vaccines are currently recommended as 2-dose HPV vaccine schedule separated by 6 months in boys and girls under the age of 15, although emerging data suggest that a single dose of the HPV vaccines offers similarly strong protective antibody responses. At present, very little is known about the characteristics of the antibody response following reduced-dose HPV vaccine schedules. In this study, we examined the antibody profiles of adolescent Fijian girls who previously received 1 or 2 doses of 4vHPV (Gardasil®, Merck Inc.) 6 years earlier, compared to those who received 3 doses. A prospective cohort study was undertaken in 200 Fijian girls (aged 15-19 years at the commencement of the study) who previously received 0, 1, 2 or 3 doses of 4vHPV in 2008-2009. Blood was taken before and 28 days following a booster dose of 2vHPV (Cervarix®, GSK). HPV16/18-specific antibody subclasses (total IgG, IgG1, IgG2, IgG3, IgG4, IgA1, IgA2 and IgM) in serum were measured using a HPV multiplex immunoassay on a subset of the study samples, with equal numbers of participants in each dose group (N=80, 20/group). After 6 years, there were no significant differences in antibody profiles between the 2- and 3-dose groups. HPV16/18-specific geometric mean FI were significantly lower for the 1-dose group compared to the 2-dose group in terms of IgG (HPV16; p=0.0006, HPV18; p=0.0071 respectively), IgG1 (HPV16; p=0.0246), and IgA1 (HPV16; p=0.0042). No significant differences were found between these groups for IgM, IgA2, IgG2, IgG3 and IgG4. Post-2vHPV, HPV16/18-specific antibody profiles were similar between groups who previously received 1, 2 or 3 doses of 4vHPV. These data suggest that 1-dose vaccine schedules may induce functional antibody responses similar to 2 or 3 doses, and provide immunological evidence supporting 1-dose HPV vaccine schedules in LMICs.