Evaluation of Durability of a Single Dose of the Bivalent HPV Vaccine: The CVT Trial

Abstract

Background The authors investigated the durability of vaccine efficacy (VE) against human papillomavirus (HPV)16 or 18 infections and antibody response among nonrandomly assigned women who received a single dose of the bivalent HPV vaccine compared with women who received multiple doses and unvaccinated women. Methods HPV infections were compared between HPV16 or 18-vaccinated women aged 18 to 25 years who received one (N = 112), two (N = 62), or three (N = 1365) doses, and age- and geography-matched unvaccinated women (N = 1783) in the long-term follow-up of the Costa Rica HPV Vaccine Trial. Cervical HPV infections were measured at two study visits, approximately 9 and 11 years after initial HPV vaccination, using National Cancer Institute next-generation sequencing TypeSeq1 assay. VE and 95% confidence intervals (CIs) were estimated. HPV16 or 18 antibody levels were measured in all one- and two-dose women, and a subset of three-dose women, using a virus-like particle-based enzyme-linked immunosorbent assay (n = 448). Results Median follow-up for the HPV-vaccinated group was 11.3 years (interquartile range = 10.9–11.7 years) and did not vary by dose group. VE against prevalent HPV16 or 18 infection was 80.2% (95% CI = 70.7% to 87.0%) among three-dose, 83.8% (95% CI = 19.5% to 99.2%) among two-dose, and 82.1% (95% CI = 40.2% to 97.0%) among single-dose women. HPV16 or 18 antibody levels did not qualitatively decline between years four and 11 regardless of the number of doses given, although one-dose titers continue to be statistically significantly lower compared with two- and three-dose titers. Conclusion More than a decade after HPV vaccination, single-dose VE against HPV16 or 18 infection remained high and HPV16 or 18 antibodies remained stable. A single dose of bivalent HPV vaccine may induce sufficiently durable protection that obviates the need for more doses.

Australia’s Role in Pneumococcal and Human Papillomavirus Vaccine Evaluation in Asia-Pacific

“…This was the first study to demonstrate the generation of immunological memory following just one dose of HPV vaccine, as well as the first to report on the immunogenicity following a mixed vaccine schedule [ 94 ]. These findings, along with other studies on the single dose schedule [ 96 , 97 , 98 , 99 ], supported further research into this field [ 100 , 101 ], leading to several ongoing Phase III clinical trials [ 98 , 102 , 103 ]. It is, however, important to note that the clinical relevance of lower antibodies generated following one dose of HPV vaccine is unknown since there is no identified immune correlate of protection.…”

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“…The duration of protection thus represents a critical issue for the overall, especially long-term, effectiveness of HPV prophylactic vaccines. Indeed, vaccine-induced antibodies peaked one month after the last immunization but could still be detected 11 years after administration of the current VLP vaccines (55). Memory B cells and long-lived plasma cells are key to immunization longevity and long-term protection.…”

Modelling the impact of prevention strategies on cervical cancer incidence in South Africa

“…Around 60% received both doses 11 . In the model, we assume that all vaccinated women receive 100% lifelong protection against infection with HPV types 16 and 18, as well as against types 31/33/45 in 50% of women, regardless of the number of doses 35‐37 . Based on immunogenicity induced by vaccination among women living with HIV 38,39 we assume the same efficacy against new HPV infection for HIV negative and positive women.…”