Potential impact of catch-up HPV vaccination on HPV prevalence and cervical cancer incidence among women living with HIV in South Africa: results from two mathematical models

IntroductionWomen living with HIV (WLHIV) face an increased risk of cervical cancer (CC). With inequitable HPV vaccine access and a programmatic focus on girls-only school-based delivery, many WLHIV in high HIV prevalence countries remain vulnerable to HPV infection and CC. We assessed the incremental impact of adding catch-up vaccination for WLHIV in South Africa. MethodsWe used two independently developed HPV/CC and HIV transmission models to predict the incremental impact of catch-up HPV vaccination for WLHIV compared to routine-only vaccination of girls aged 9-14 (90% cohort coverage) from 2020 onward using a nonavalent vaccine (lifelong 100% protection). We assessed two catch-up scenarios vaccinating WLHIV aged 15-24 or 15+ (attaining 90% cohort coverage for at least three years), maintaining baseline CC screening. We report the predicted median annual prevalence of vaccine-type high-risk HPV (VT HR-HPV), CC incidence, and cumulative fraction of CC averted compared to routine-only vaccination among WLHIV overall (age-standardized) and by age. ResultsWith routine-only vaccination, overall coverage among WLHIV remained substantially (>50%) lower than in all women for 35-40 years, with gaps persisting even after 80 years. Adding catch-up vaccination for WLHIV aged 15-24 increased coverage and benefits mainly among young WLHIV, with the largest annual reductions (relative to routine-only vaccination) in VT HR-HPV prevalence and CC incidence for WLHIV <30 years, reaching up to 36-52% across models within 15 years and 38-100% after 15-25 years, respectively. If catch-up included WLHIV aged 15+, overall vaccination coverage among WLHIV would immediately increase to 90%, extending benefits to older WLHIV -reducing peak annual relative reductions in CC incidence among WLHIV 50+ by an extra 19%-points compared to catch-up vaccination of WLHIV aged 15-24, and shifting the peak 25 years earlier. Over 55-60 years, catch-up vaccination of WLHIV aged 15-24 and 15+ could avert up to 3-8% and 14% of CC cases among WLHIV, respectively. ConclusionsCatch-up vaccination of WLHIV can reduce their CC burden in the short to medium term, even in the presence of girls-only routine vaccination programs with high cohort coverage. To maximize impact, vaccines should be offered to WLHIV of all ages, not only younger women.