About the Authors

José Humberto Tavares Guerreiro Fregnani

mdfregnani@terra.com.br

Affiliations Research and Teaching Institute – Barretos Cancer Hospital (IEP – HCB), Barretos, Brazil, National Institute of Science and Technology of the Diseases Associated to the Papillomavirus (INCT-HPV)/Santa Casa de São Paulo Medical School- FCMSCSP), São Paulo, Brazil

André Lopes Carvalho

Affiliation Research and Teaching Institute – Barretos Cancer Hospital (IEP – HCB), Barretos, Brazil

José Eluf-Neto

Affiliations National Institute of Science and Technology of the Diseases Associated to the Papillomavirus (INCT-HPV)/Santa Casa de São Paulo Medical School- FCMSCSP), São Paulo, Brazil, Departament of Preventive Medicine – Faculdade de Medicina, Universidade de São Paulo (USP), São Paulo, Brazil

Karina de Cássia Braga Ribeiro

Affiliations National Institute of Science and Technology of the Diseases Associated to the Papillomavirus (INCT-HPV)/Santa Casa de São Paulo Medical School- FCMSCSP), São Paulo, Brazil, Departament of Social Medicine – Santa Casa de São Paulo Medical School (FCMSCSP), São Paulo, Brazil

Larissa de Melo Kuil

Affiliation Research and Teaching Institute – Barretos Cancer Hospital (IEP – HCB), Barretos, Brazil

Tauana Arcadepani da Silva

Affiliation Research and Teaching Institute – Barretos Cancer Hospital (IEP – HCB), Barretos, Brazil

Silvia Lapola Rodrigues

Affiliation Research and Teaching Institute – Barretos Cancer Hospital (IEP – HCB), Barretos, Brazil

Edmundo Carvalho Mauad

Affiliation Research and Teaching Institute – Barretos Cancer Hospital (IEP – HCB), Barretos, Brazil

Adhemar Longatto-Filho

Affiliations Research and Teaching Institute – Barretos Cancer Hospital (IEP – HCB), Barretos, Brazil, National Institute of Science and Technology of the Diseases Associated to the Papillomavirus (INCT-HPV)/Santa Casa de São Paulo Medical School- FCMSCSP), São Paulo, Brazil, Medical Research Laboratory 14– Medicine School of Universidade de São Paulo (USP), São Paulo, Brazil

Luisa Lina Villa

Affiliation National Institute of Science and Technology of the Diseases Associated to the Papillomavirus (INCT-HPV)/Santa Casa de São Paulo Medical School- FCMSCSP), São Paulo, Brazil

Competing Interests

This study was partially supported by Merck & Co., Inc. Merck & Co., Inc. provided the vaccine by Merck Investigator Studies Program (MISP) to the first author (José Humberto Fregnani, on behalf of Barretos Cancer Hospital). Luisa Lina Villa participated in several clinical trials that validated the safety and efficacy of the quadrivalent vaccine and is a member of the study advisory committee of Merck & Co., Inc. She never received any grant from the company to support her research activities. This does not alter the authors' adherence to all the PLoS ONE policies on sharing data and materials.

Author Contributions

Conceived and designed the experiments: JHTGF ALC JEN KdCBR ECM ALF LLV. Performed the experiments: JHTGF LMK TAdS SLR. Analyzed the data: JHTGF LMK TAdS SLR. Wrote the paper: JHTGF ALC JEN ECM ALF LLV.