• The ESCUDDO study was published by The New England Journal of Medicine, classified as one of the most prestigious journals for its high impact on medical science and health.
• This journal only accepts 5% of the manuscripts received.

San José, December 2025. The results of the ESCUDDO study, conducted by the Costa Rican Agency for Biomedical Research of the Inciensa Foundation (ACIB-FUNIN), in collaboration with the National Cancer Institute of the United States, were published this December 3 in the prestigious scientific journal The New England Journal of Medicine (NEJM), considered the most important worldwide, for its high level of scientific influence.

This journal only accepts 5% of the manuscripts received, since one of the aspects to be evaluated is that they are investigations whose results can guide medical practices, clinical guidelines and health policies, as it has been done by the Costa Rican ESCUDDO study.

This research, which began in Costa Rica in 2017, demonstrated that a single dose of either of the two main human papillomavirus (HPV) vaccines is no less effective than two doses in protecting against HPV types 16 and 18. These two HPV types are responsible for more than 70% of cervical cancer cases worldwide. Furthermore, one dose of the nonvalent vaccine is no less effective than two doses, meaning it protects against all nine HPV types that cause approximately 90% of cervical cancer and genital wart cases.

The first findings of ESCUDDO were announced last April at the annual meeting of the American Association for Cancer Research (AACR), globally considered one of the most important scientific events in this field.

“Currently, the World Health Organization recommends administering one or two doses of the vaccine to children aged 9 to 14, leaving the number of doses to the discretion of governments. The ESCUDDO results provide robust evidence for regulatory bodies to consolidate their recommendation of vaccination to a single dose, opening the door to broader global coverage, especially in low- and middle-income countries, where access to complete vaccination schedules has been limited for economic or logistical reasons,” emphasizes Dr. Carolina Porras, Director of Biomedical Research of ACIB-FUNIN, principal investigator of ESCUDDO and of the scientific article published in NEJM.

The ESCUDDO study is the only one worldwide that sought to verify whether the protection provided by one dose of the HPV vaccine was no less than that provided by two doses, so its results were of special attention to various international organizations and authorities.

Currently, 78% of Latin American and Caribbean countries use a single dose in their vaccination schedule, according to the Pan American Health Organization, highlighting the contribution of this Costa Rican study to global public health. In Costa Rica, two doses are still administered to 10-year-old girls and boys.

The publication of ESCUDDO’s scientific article in The New England Journal of Medicine reflects the outstanding work carried out in our country by Costa Rican scientists who have dedicated decades to researching ways to prevent HPV and cervical cancer. A study of this magnitude and importance is a national milestone in biomedical research, given that this journal has a 200-year history and is a leading publication in more than 150 countries, placing Costa Rica on a prominent global stage and on the height with other countries that have been recognized for years for their scientific contributions,” explains Dr. Rolando Herrero, Scientific Director of ACIB-FUNIN and senior author of the publication.

The ESCUDDO study was conducted in more than 50 cantons of Costa Rica, with the participation of over 23,000 women between the ages of 12 and 20. This research was carried out in collaboration with the National Cancer Institute of the United States (NCI).

“We extend our deepest gratitude to the young women and girls of Costa Rica who participated in the ESCUDDO study in an extraordinary display of solidarity with all women and their families,” emphasizes Dr. Porras.

ACIB-FUNIN will continue evaluating the duration of protection provided by a single dose. This Costa Rican non-governmental, non-profit organization has leading researchers who have dedicated more than 30 years to conducting biomedical research with a significant impact on global public health.