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Single-dose HPV vaccine immunity: is there a role for non-neutralizing antibodies? Trends Immunol 2022; 43:815-825. [PMID: 35995705 DOI: 10.1016/j.it.2022.07.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 07/28/2022] [Accepted: 07/30/2022] [Indexed: 11/22/2022]
Abstract
A single dose of human papillomavirus (HPV) vaccine against HPV infection (prerequisite for cervical cancer) appears to be as efficacious as two or three doses, despite inducing lower antibody titers. Neutralizing antibodies are thought to be the primary mediator of protection, but the threshold for protection is unknown. Antibody functions beyond neutralization have not been explored for HPV vaccines. Here, we discuss the immune mechanisms of HPV vaccines, with a focus on non-neutralizing antibody effector functions. In the context of single-dose HPV vaccination where antibody is limiting, we propose that non-neutralizing antibody functions may contribute to preventing HPV infection. Understanding the immunological basis of protection for single-dose HPV vaccination will provide a rationale for implementing single-dose HPV vaccine regimens.
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Pitisuttithum P, Dhitavat J, Sirivichayakul C, Pitisuthitham A, Sabmee Y, Chinwangso P, Kerdsomboon C, Fortuna L, Spiegel J, Chauhan M, Poredi IK, van den Biggelaar AH, Wijagkanalan W, Viviani S, Mansouri S, Pham HT. Antibody persistence 2 and 3 years after booster vaccination of adolescents with recombinant acellular pertussis monovalent aP gen or combined TdaP gen vaccines. EClinicalMedicine 2021; 37:100976. [PMID: 34386749 PMCID: PMC8343263 DOI: 10.1016/j.eclinm.2021.100976] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/20/2021] [Accepted: 06/04/2021] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Recombinant pertussis vaccines inducing long-lasting immune responses could help to control the rise in pertussis. We here report on persisting antibody responses 2 and 3 years after booster vaccination with a new generation recombinant acellular pertussis vaccine. METHODS Participants of a phase 2/3 randomised-controlled clinical trial with a monovalent pertussis vaccine containing genetically inactivated pertussis toxin (aPgen) or its tetanus and diphtheria toxoids combination (TdaPgen), or a chemically detoxified comparator vaccine (Tdapchem), (originally conducted between July and August 2015) were invited to participate in observational studies of persisting antibody responses 2 and 3 years after vaccination. Serum IgG against pertussis toxin (PT-IgG) and filamentous hemagglutinin (FHA-IgG) were assessed by ELISA, and PT-neutralising antibodies (PT-Nab) by Chinese Hamster Ovary cell assay. FINDINGS Waning of antibodies stabilised in aPgen and TdaPgen vaccinees 2 and 3 years after vaccination. Three years post-vaccination PT-neutralising antibodies remained 4·6-fold (95% Confidence Interval (CI) 2·6-8·1) and 3·7-fold (95% CI 2·2-6·1) higher, PT-IgG antibodies 3·0-fold (95% CI 2·2-4·1) and 2·5-fold (95% CI 1·9-3·3) higher, and FHA-IgG antibodies 1·8-fold (95% CI 1·3-2·5) and 1·6-fold (95% CI 1·2-2·1) higher than baseline in aPgen and TdaPgen recipients, respectively. In the Tdapchem group, PT-neutralising and PT-IgG and FHA-IgG antibodies were back at baseline levels 2 years post-vaccination. Three years post-vaccination seroconversion rates for PT-neutralising antibodies were 65·0% (95% CI 44·1-85·9) and 55·0% (95% CI 33·2-76·8) in aPgen and TdaPgen recipients, respectively. INTERPRETATION Considering the persistence of elevated antibody responses 3 years post-booster vaccination, genetically detoxified monovalent aPgen and TdaPgen vaccines can be expected to induce longer-lasting protection than chemically inactivated Tdap vaccines. FUNDING BioNet-Asia.
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Affiliation(s)
- Punnee Pitisuttithum
- Vaccine Trial Centre, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok 10400, Thailand
| | - Jittima Dhitavat
- Vaccine Trial Centre, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok 10400, Thailand
| | - Chukiat Sirivichayakul
- Vaccine Trial Centre, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok 10400, Thailand
| | - Arom Pitisuthitham
- Vaccine Trial Centre, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok 10400, Thailand
| | - Yupa Sabmee
- Vaccine Trial Centre, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok 10400, Thailand
| | - Pailinrut Chinwangso
- BioNet-Asia Co., Ltd., 19 Soi Udomsuk 37, Sukhumvit 103 Road, Bangjak, Prakanong, Bangkok 10260, Thailand
| | - Chawanee Kerdsomboon
- BioNet-Asia Co., Ltd., 19 Soi Udomsuk 37, Sukhumvit 103 Road, Bangjak, Prakanong, Bangkok 10260, Thailand
| | - Librada Fortuna
- BioNet-Asia Co., Ltd., 19 Soi Udomsuk 37, Sukhumvit 103 Road, Bangjak, Prakanong, Bangkok 10260, Thailand
| | - Jane Spiegel
- BioNet-Asia Co., Ltd., 19 Soi Udomsuk 37, Sukhumvit 103 Road, Bangjak, Prakanong, Bangkok 10260, Thailand
| | - Mukesh Chauhan
- BioNet-Asia Co., Ltd., 19 Soi Udomsuk 37, Sukhumvit 103 Road, Bangjak, Prakanong, Bangkok 10260, Thailand
| | - Indrajeet Kumar Poredi
- BioNet-Asia Co., Ltd., 19 Soi Udomsuk 37, Sukhumvit 103 Road, Bangjak, Prakanong, Bangkok 10260, Thailand
| | | | - Wassana Wijagkanalan
- BioNet-Asia Co., Ltd., 19 Soi Udomsuk 37, Sukhumvit 103 Road, Bangjak, Prakanong, Bangkok 10260, Thailand
| | - Simonetta Viviani
- BioNet-Asia Co., Ltd., 19 Soi Udomsuk 37, Sukhumvit 103 Road, Bangjak, Prakanong, Bangkok 10260, Thailand
| | - Souad Mansouri
- BioNet-Asia Co., Ltd., 19 Soi Udomsuk 37, Sukhumvit 103 Road, Bangjak, Prakanong, Bangkok 10260, Thailand
- Corresponding author.
| | - Hong Thai Pham
- BioNet-Asia Co., Ltd., 19 Soi Udomsuk 37, Sukhumvit 103 Road, Bangjak, Prakanong, Bangkok 10260, Thailand
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Asatryan A, Meyer N, Scherbakov M, Romanenko V, Osipova I, Galustyan A, Shamsheva O, Latysheva T, Myasnikova T, Baudson N, Dodet M, Xavier S, Harrington L, Kuznetsova A, Campora L, Van den Steen P. Immunogenicity, safety, and reactogenicity of combined reduced-antigen-content diphtheria-tetanus-acellular pertussis vaccine administered as a booster vaccine dose in healthy Russian participants: a phase III, open-label study. Hum Vaccin Immunother 2021; 17:723-730. [PMID: 32845735 PMCID: PMC7993191 DOI: 10.1080/21645515.2020.1796423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
As vaccine-induced immunity and protection following natural pertussis infection wane over time, adults and adolescents may develop pertussis and become transmitters to unprotected infants. In Russia, diphtheria and tetanus but not pertussis-containing vaccines are registered for older children, adolescents, or adults. The reduced-antigen-content diphtheria toxoid, tetanus toxoid, and acellular pertussis (dTpa) vaccine (Boostrix, GSK) was developed for booster vaccination of children ≥4 years of age, adolescents, and adults. A phase III, open-label, non-randomized study was performed in eight centers in Russia between January and July 2018. The objective of this study was to assess immunogenicity, reactogenicity and safety of a single dose of dTpa vaccine in healthy Russian participants ≥4 years of age (age categories 4-9 years, 10-17 years, 18-64 years, and ≥65 years). At 1 month post-booster vaccination, across all age groups, >99.0% of participants were seroprotected against diphtheria and tetanus and >96.0% of participants were seropositive for anti-pertussis antibodies. For all antibodies across all age groups, antibody GMCs increased from pre- to 1 month post-booster vaccination and booster responses to diphtheria (in 71.5% of participants), tetanus (85.3%), and pertussis antigens (≥85.6%) were observed. One serious adverse event that was not causally related to the study vaccine was reported. No fatal cases were reported throughout the study period. In conclusion, administration of the dTpa vaccine as a booster dose in healthy Russian participants induced a robust immune response to all vaccine antigens and was generally well tolerated across all age groups.
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Affiliation(s)
| | | | | | | | | | - Anna Galustyan
- Medical Technologies Ltd, St. Petersburg, Russian Federation.,Federal State Budgetary Educational Institution of Higher Education, St. Petersburg State Pediatric Medical University of the Ministry of Healthcare of the Russian Federation, St. Petersburg, Russian Federation
| | - Olga Shamsheva
- Pirogov Russian National Research Medical University, Moscow, Russian Federation
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McAlister SM, van den Biggelaar AHJ, Woodman TL, Hutton H, Thornton RB, Richmond PC. An observational study of antibody responses to a primary or subsequent pertussis booster vaccination in Australian healthcare workers. Vaccine 2021; 39:1642-1651. [PMID: 33589299 DOI: 10.1016/j.vaccine.2021.01.041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 11/23/2020] [Accepted: 01/16/2021] [Indexed: 11/29/2022]
Abstract
Adult pertussis vaccination is increasingly recommended to control pertussis in the community. However, there is little data on the duration and kinetics of immunity to pertussis boosters in adults. We compared IgG responses to vaccination with a tetanus, low-dose diphtheria, low-dose acellular pertussis (Tdap) booster at 1 week, 1 month and 1 year post-vaccination in whole-cell (wP)-primed Australian paediatric healthcare workers who had received an adult Tdap booster 5-12 years previously, to those who received their first Tdap booster. Tdap vaccination was well tolerated in both groups. Previously boosted adults had significantly higher pre-vaccination IgG concentrations for all vaccine-antigens, and more were seropositive for pertussis toxin (PT)-specific IgG (≥ 5 IU/mL) (69.5%; 95% confidence interval (CI) 59.5-79.5) than adults in the naïve group (45.2%; 95% CI 32.8-57.5). Tdap vaccination significantly increased IgG responses 1 month post-vaccination in both groups. This increase was more rapid in previously boosted than in naïve adults, with geometric mean fold-increases in PT-IgG at 1 week post vaccination of 3.6 (95% CI 2.9-4.3) and 2.6 (95% CI 2.2-3.2), respectively. Antibody waning between 1 month and 1 year post-vaccination was similar between groups for IgG specific to PT and filamentous haemagglutinin (FHA), but was faster for IgG against pertactin (PRN) in the naïve group (GMC ratio 0.36; 95% CI 0.31-0.42) than the previously boosted group (GMC ratio 0.45; 95% CI 0.39-0.50). At baseline, all but one adult had protective IgG titres against tetanus toxin (TT) (≥ 0.1 IU/mL), and 75.6% in the previously boosted and 61.3% in the naïve group had protective IgG titres against diphtheria toxoid (DT) of ≥ 0.1 IU/mL. This study shows that pertussis immune memory is maintained up to 12 years after Tdap vaccination in wP-primed Australian adults. There was no evidence that pertussis immune responses waned faster after a booster dose. These findings support current recommendations of repeating Tdap booster vaccination in paediatric healthcare workers at least every 10 years. Clinical trials registry: ACTRN12615001262594.
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Affiliation(s)
- Sonia M McAlister
- Vaccine Trials Group, Wesfarmers Centre of Vaccines & Infectious Diseases, Telethon Kids Institute, Perth, Western Australia, Australia; Division of Paediatrics, School of Medicine, The University of Western Australia, Perth, Western Australia, Australia.
| | - Anita H J van den Biggelaar
- Vaccine Trials Group, Wesfarmers Centre of Vaccines & Infectious Diseases, Telethon Kids Institute, Perth, Western Australia, Australia; Division of Paediatrics, School of Medicine, The University of Western Australia, Perth, Western Australia, Australia
| | - Tabitha L Woodman
- Vaccine Trials Group, Wesfarmers Centre of Vaccines & Infectious Diseases, Telethon Kids Institute, Perth, Western Australia, Australia; Division of Paediatrics, School of Medicine, The University of Western Australia, Perth, Western Australia, Australia
| | - Heidi Hutton
- Vaccine Trials Group, Wesfarmers Centre of Vaccines & Infectious Diseases, Telethon Kids Institute, Perth, Western Australia, Australia
| | - Ruth B Thornton
- Vaccine Trials Group, Wesfarmers Centre of Vaccines & Infectious Diseases, Telethon Kids Institute, Perth, Western Australia, Australia; Division of Paediatrics, School of Medicine, The University of Western Australia, Perth, Western Australia, Australia
| | - Peter C Richmond
- Vaccine Trials Group, Wesfarmers Centre of Vaccines & Infectious Diseases, Telethon Kids Institute, Perth, Western Australia, Australia; Division of Paediatrics, School of Medicine, The University of Western Australia, Perth, Western Australia, Australia; Departments of Immunology and General Paediatrics, Perth Children's Hospital, Perth, Western Australia, Australia
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Esteve M, Carreras R, Casas I, Peña P, Guixeras A, Torrecillas S, Bretau F, Subirats P, Alonso A, Soldevila N, Costa J, Domínguez A. The immune status against tetanus and diphtheria in healthcare workers in Catalonia. Vaccine 2020; 38:2646-2650. [DOI: 10.1016/j.vaccine.2020.01.076] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 01/23/2020] [Accepted: 01/24/2020] [Indexed: 01/02/2023]
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Yenkoidiok-Douti L, Jewell CM. Integrating Biomaterials and Immunology to Improve Vaccines Against Infectious Diseases. ACS Biomater Sci Eng 2020; 6:759-778. [PMID: 33313391 PMCID: PMC7725244 DOI: 10.1021/acsbiomaterials.9b01255] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Despite the success of vaccines in preventing many infectious diseases, effective vaccines against pathogens with ongoing challenges - such as HIV, malaria, and tuberculosis - remain unavailable. The emergence of new pathogen variants, the continued prevalence of existing pathogens, and the resurgence of yet other infectious agents motivate the need for new, interdisciplinary approaches to direct immune responses. Many current and candidate vaccines, for example, are poorly immunogenic, provide only transient protection, or create risks of regaining pathogenicity in certain immune-compromised conditions. Recent advances in biomaterials research are creating new potential to overcome these challenges through improved formulation, delivery, and control of immune signaling. At the same time, many of these materials systems - such as polymers, lipids, and self-assembly technologies - may achieve this goal while maintaining favorable safety profiles. This review highlights ways in which biomaterials can advance existing vaccines to safer, more efficacious technologies, and support new vaccines for pathogens that do not yet have vaccines. Biomaterials that have not yet been applied to vaccines for infectious disease are also discussed, and their potential in this area is highlighted.
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Affiliation(s)
- Lampouguin Yenkoidiok-Douti
- Fischell Department of Bioengineering, University of Maryland, College Park, 8278 Paint Branch Drive, College Park, MD, 20742, United States
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institute of Health, Rockville, MD, 20852, United States
| | - Christopher M. Jewell
- Fischell Department of Bioengineering, University of Maryland, College Park, 8278 Paint Branch Drive, College Park, MD, 20742, United States
- Department of Veterans Affairs, VA Maryland Health Care System, 10. N Green Street, Baltimore, MD 21201, USA
- Robert E. Fischell Institute for Biomedical Devices, 8278 Paint Branch Drive, College Park, MD 20742, United States
- Department of Microbiology and Immunology, University of Maryland Medical School, 685 West Baltimore Street, HSF-I Suite 380, Baltimore, MD, 21201, United States
- Marlene and Stewart Greenebaum Cancer Center, 22 S. Greene Street, Suite N9E17, Baltimore, MD 21201, United States
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Havers FP, Moro PL, Hunter P, Hariri S, Bernstein H. Use of Tetanus Toxoid, Reduced Diphtheria Toxoid, and Acellular Pertussis Vaccines: Updated Recommendations of the Advisory Committee on Immunization Practices - United States, 2019. MMWR-MORBIDITY AND MORTALITY WEEKLY REPORT 2020; 69:77-83. [PMID: 31971933 PMCID: PMC7367039 DOI: 10.15585/mmwr.mm6903a5] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Since 2005, a single dose of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine has been recommended by the Advisory Committee on Immunization Practices (ACIP) for adolescents and adults (1,2). After receipt of Tdap, booster doses of tetanus and diphtheria toxoids (Td) vaccine are recommended every 10 years or when indicated for wound management. During the October 2019 meeting of ACIP, the organization updated its recommendations to allow use of either Td or Tdap where previously only Td was recommended. These situations include decennial Td booster doses, tetanus prophylaxis when indicated for wound management in persons who had previously received Tdap, and for multiple doses in the catch-up immunization schedule for persons aged ≥7 years with incomplete or unknown vaccination history. Allowing either Tdap or Td to be used in situations where Td only was previously recommended increases provider point-of-care flexibility. This report updates ACIP recommendations and guidance regarding the use of Tdap vaccines (3).
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Liu Y, Mo X, Yu X, Wang J, Tian J, Kuang J, Peng J. Insufficient knowledge and inappropriate practices of emergency doctors towards tetanus prevention in trauma patients: a pilot survey. Hum Vaccin Immunother 2019; 16:349-357. [PMID: 31625792 PMCID: PMC7062443 DOI: 10.1080/21645515.2019.1653745] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
China has a shocking number of tetanus cases in the world, but little research has investigated doctors’ knowledge of and practices in tetanus prophylaxis, especially tetanus vaccination. To this end, we conducted a pilot study on 197 emergency doctors using a mixed method of web-based (163; 82.8%) and paper-based (34; 17.2%) surveys. There was no difference between the two groups except for the percentage of doctors receiving a tetanus booster in the past 10 years and the responses to question 11. Surprisingly, only 28.9% of doctors had received formal training on tetanus immunization and only 21.3% had themselves received a tetanus vaccine booster in the past 10 years. Furthermore, only 14.2% of the respondents confirmed the availability of the tetanus vaccine in their respective institutions. Finally, the correct rates and Tetanus-immune-globulin (TIG)-only option rates for questions 11–15 were unsatisfactory. Our results showed that most emergency doctors’ knowledge and practices strayed from the recommendations of Advisory Committee on Immunization Practices (ACIP): 1) TIG alone for most trauma patients instead of vaccine was an overused treatment approach. 2) Most of the emergency doctors lacked formal training on and knowledge of tetanus vaccination. 3) Even the emergency doctors themselves were not properly vaccinated. 4) The tetanus vaccine was only available in a small number of the respondents’ institutions. The findings of this study suggest an urgent need to improve this dire situation.
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Affiliation(s)
- Yong Liu
- Intensive Care Unit, Shenzhen Hospital, Southern Medical University, Shenzhen, PR China
| | - Xichao Mo
- Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou, PR China
| | - Xiaxia Yu
- Department of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, PR China
| | - Jinxin Wang
- Intensive Care Unit, Shenzhen Hospital, Southern Medical University, Shenzhen, PR China
| | - Jinfei Tian
- Intensive Care Unit, Shenzhen Hospital, Southern Medical University, Shenzhen, PR China
| | - Jun Kuang
- Department of Thoracic Surgery, Shenzhen Hospital, Southern Medical University, Shenzhen, PR China
| | - Jie Peng
- Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou, PR China
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Lazcano-Ponce E, Carnalla-Cortés M, Barrientos-Gutiérrez T, Torres-Ibarra L, Cruz-Valdez A, Salmerón J, Hernández-Ávila M. The effect of a booster dose of HPV tetravalent vaccine after 51 months: implications for extended vaccination schedules. SALUD PUBLICA DE MEXICO 2019; 60:666-673. [PMID: 30699272 DOI: 10.21149/10183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 11/27/2018] [Indexed: 11/06/2022] Open
Abstract
OBJECTIVE To asses the non-inferiority between two differ- ent vaccination schedules one month after the administration of the third dose. MATERIALS AND METHODS We evaluated the anti-HPV 16/18 antibody titers induced by quadrivalent HPV vaccine administered using two different schedules in girls 9 to 10-year-old girls: a traditional (0-2-6) and an alterna- tive (0-6-50). Blood samples were collected at month 7, 21 and 51. RESULTS The antibody geometric mean titer ratios one month after the application of the third dose -month 51 for the alternative and month 7 for the traditional- were 1.55 for HPV16 (95%CI, 1.15-2.08) and 1.53 for HPV18 (95%CI, 1.12-2.09). The seropositive rate was above 99% in both groups. CONCLUSIONS The application of an alternative 3-dose schedule in 9 to 10-year-old girls induces a non-inferior immune response compared to the standard one month after the last dose. Further research is needed to understand the minimal number of doses and their timing to provide the best coverage for HPV infection.
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Affiliation(s)
- Eduardo Lazcano-Ponce
- Centro de Investigación en Salud Poblacional, Instituto Nacional de Salud Pública. Cuernavaca, Morelos, Mexico
| | - Martha Carnalla-Cortés
- Centro de Investigación en Salud Poblacional, Instituto Nacional de Salud Pública. Cuernavaca, Morelos, Mexico
| | | | - Leticia Torres-Ibarra
- Centro de Investigación en Salud Poblacional, Instituto Nacional de Salud Pública. Cuernavaca, Morelos, Mexico
| | - Aurelio Cruz-Valdez
- Centro de Investigación en Salud Poblacional, Instituto Nacional de Salud Pública. Cuernavaca, Morelos, Mexico
| | - Jorge Salmerón
- Centro de Investigación en Salud Poblacional, Instituto Nacional de Salud Pública. Cuernavaca, Morelos, Mexico.,Centro de Investigación en Políticas, Población y Salud, Facultad de Medicina, Universidad Nacional Autónoma de México. Ciudad de México, México
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