Dr. Sabrina Tsang, a current CPFP Fellow housed in the NCI Division of Cancer Epidemiology and Genetics (DCEG), recently published a manuscript titled “Durability of Cross-Protection by Different Schedules of the Bivalent HPV Vaccine: the CVT Trial.” The piece was released February 24, 2020, in the Journal of the National Cancer Institute.
Persistent infection with carcinogenic human papillomavirus (HPV) is a necessary cause of cervical cancer, with HPV types 16/18 causing about 70% of all cervical cancer cases and HPV31/33/45 accounting for another 13%. The Costa Rica HPV Vaccine Trial (CVT) has previously documented cross-protection of the bivalent HPV vaccine against HPV31/33/45 up to seven years after vaccination, even with one dose of the vaccine. However, the durability of such protection remained unknown. In this study, Dr. Tsang and her collaborators evaluated the efficacy of different vaccine schedules against HPV31/33/45 out to 11 years post-vaccination, also expanding to other non-targeted HPV types.
The study determined that significant cross-protection afforded by the bivalent vaccine against HPV31/33/45 was sustained and remained stable over 11 years. Dr. Tsang emphasizes the impact of the study results: “Our findings on the durability of cross-protective efficacy of the bivalent vaccine suggest that it may protect against a greater percentage of cervical cancers than researchers had anticipated.” Read more about this study and a complementary study led by Dr. Tsang’s NCI DCEG preceptor, Dr. Aimée Kreimer, in NCI’s Cancer Currents Blog.
After identifying cross-protected HPV types, Dr. Tsang will conduct a follow-up study to evaluate vaccine efficacy at the HPV lineage level. She hopes that the genetics of HPV can help shed light on the phenomenon of cross-protection.