Bornstein, JacobRoux, SuritaKjeld, LoneHuang, Li-MinDobson, SimonPitisuttithum, PunneeDiez, JavierSchilling, AndreaAriffin, HanyTytus, RichardRupp, RichardSenders, ShellyEngel, EliFerris, DaronKim, Yae-JeanTae, YoungKurugol, ZaferBautista, OliverNolan, KatrinaSankaranarayanan, SandhyaSaah, AlfredLuxembourg, Alain2022-04-012022-04-012021Bornstein J, Roux S, Kjeld Petersen L, Huang LM, Dobson SR, Pitisuttithum P, Diez-Domingo J, Schilling A, Ariffin H, Tytus R, Rupp R, Senders S, Engel E, Ferris D, Kim YJ, Tae Kim Y, Kurugol Z, Bautista O, Nolan KM, Sankaranarayanan S, Saah A, Luxembourg A. Three-Year Follow-up of 2-Dose Versus 3-Dose HPV Vaccine. Pediatrics. 2021 Jan;147(1):e20194035. doi: 10.1542/peds.2019-4035https://doi.org/10.1542/peds.2019-4035http://hdl.handle.net/11447/5892BACKGROUND AND OBJECTIVES: Human papillomavirus (HPV) antibody responses to the 9-valent abstract human papillomavirus (9vHPV) vaccine among girls and boys (aged 9–14 years) receiving 2- dose regimens (months 0, 6 or 0, 12) were noninferior to a 3-dose regimen (months 0, 2, 6) in young women (aged 16–26 years) 4 weeks after last vaccination in an international, randomized, open-label trial (NCT01984697). We assessed response durability through month 36. METHODS: Girls received 2 (months 0 and 6 [0, 6]: n = 301; months 0 and 12 [0, 12]: n = 151) or 3 doses (months 0,2, and 6 [0, 2, 6]: n = 301); boys received 2 doses ([0, 6]: n = 301; [0, 12]: n = 150); and young women received 3 doses ([0, 2, 6]: n = 314) of 9vHPV vaccine. Anti-HPV geometric mean titers (GMTs) were assessed by competitive Luminex immunoassay (cLIA) and immunoglobulin G-Luminex immunoassay (IgG-LIA) through month 36. RESULTS: Anti-HPV GMTs were highest 1 month after the last 9vHPV vaccine regimen dose, decreased sharply during the subsequent 12 months, and then decreased more slowly. GMTs 2 to 2.5 years after the last regimen dose in girls and boys given 2 doses were generally similar to or greater than GMTs in young women given 3 doses. Across HPV types, most boys and girlswho received 2 doses (cLIA: 81%–100%; IgG-LIA: 91%–100%) and young women who received 3 doses (cLIA: 78%–98%; IgG-LIA: 91%–100%) remained seropositive 2 to 2.5 years after the last regimen dose. CONCLUSIONS: Antibody responses persisted through 2 to 2.5 years after the last dose of a 2-dose 9vHPV vaccine regimen in girls and boys. In girls and boys, antibody responses generated by 2 doses administered 6 to 12 months apart may be sufficient to induce high-level protective efficacy through at least 2 years after the second dose.enAlphapapillomavirus / immunologyAntibodies, Viral / bloodBiomarkers / bloodDose-Response Relationship, ImmunologicPapillomavirus Vaccines / immunologyPapillomavirus Vaccines / administration & dosageFollow-Up StudiesAdolescentAdultDose-Response Relationship, ImmunologicArticle