Term immune memory responses to human papillomavirus (HPV) vaccination following 2 versus 3 doses of HPV vaccine.

Human papillomavirus (HPV) vaccines provide excellent protection from infection and disease. The minimum number of doses needed for long-term protection and the potential need for boosters are areas of continuing interest. Studies on the durability of vaccines have focused on antibodies, fewer have analyzed memory immune cells that could provide protection even when antibody levels are low. In this study, subjects who had participated in one of two trials comparing two and three doses (2D, 3D), were given an additional vaccine dose (Gardasil®9, 9vHPV) several years after the initial vaccine doses, and the magnitude of immune responses were compared. Both trials had 2D children who received doses at 0 and 6 months (G1a), 3D children 9-13 (08-001) or 9-14 (V503-010) years old at enrollment in the original trial (G2) and 3D women (age 16-26) (G3). Trial V503-010 had a second 2D group of children vaccinated at 0 and 12 months (G1b). Changes in numbers of HPV specific memory B cells (Bmem) (N = 6 per group, both studies) at 1 month and plasmablasts (PB) (08-001: N = 6 per group, V503-010: G1a N = 12, G1b N = 8, G2 N = 6, G3 N = 28) at 1 week, relative to baseline at the additional dose, were compared among groups. Changes in the geometric mean titers (GMTs) of HPV specific antibodies relative to baseline were compared (N = same as PB). Statistically significant (p < 0.05) increases in the numbers of PB, Bmem and antibody levels (GMT) were seen among subjects receiving an extra vaccine dose relative to baseline. Increases in the number of PB and Bmem were not significantly different among subjects receiving two or three doses. Thus, robust immune responses were observed and did not differ significantly among subjects vaccinated with two or three doses.
Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Denise Galloway reports financial support was provided by Merck Sharp and Dohme Pharmaceuticals. Denise Galloway reports a relationship with Merck Sharp and Dohme Pharmaceuticals that includes: consulting or advisory and funding grants. Honoraria paid from Merck to Erin M. Scherer for lectures/seminars delivered, Manish Sadarangani has been an investigator on projects funded by GlaxoSmithKline, Merck, Moderna, Pfizer and Sanofi-Pasteur. All funds have been paid to his institute, and he has not received any personal payments. Sandhya Sankaranarayanan, Alain Luxembourg and are employees of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA. Other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2025. Published by Elsevier Ltd.)