Life & Health

Guanacaste Scientists Want to Know If a Single Vaccine Dose Can Prevent HPV Infection

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A group of scientists at the Agencia Costarricense de Investigaciones Biomédicas (Costa Rican Agency for Biomedical Research), who work in Liberia, will research whether a single dose of a vaccine against the human papillomavirus (HPV) is enough to prevent young women from becoming infected while having sexual relations.


Currently two injections are required to entirely prevent HPV infection. If study results show that one dose is sufficient, the costs associated with mass vaccination campaigns will be reduced by more than half, epidemiologist and agency director Paula González told The Voice of Guanacaste.


It would allow savings on cost and facilitate the implementation [of a vaccine program]. In the poorest countries, the registry systems are insufficient, and having to vaccinate a young girl again because she left the educational system is practically impossible,” González said.



HPV is the most common sexually transmitted disease in the world. It’s also the primary cause of cervical cancer, which in 2016 affected 26 of every 100,000 women in Guanacaste. It is the third most common tumor in women in the region.


See also: “Siete dudas ginecológicas de las guanacastecas


Costa Rica does not yet offer free HPV vaccination, although the Health Ministry is evaluating the possibility. In the private health care system, each dose costs between ¢35,0000 and ¢45,000.


The benefit of getting vaccinated is greater than the cost incurred by the [Costa Rican Social Security System] when cervical cancer develops. If [cancer] is detected in an advanced state, treatment requires chemotherapy and patients must go to Hospital México [in San José]. They can’t receive treatment in Guanacaste,” said gynecologist Keren Porat, from La Anexión de Nicoya Hospital.


Mortality rates in the country have declined by 38-40% in the past 20 years thanks to all of the therapy options. This vaccine would improve these statistics even more. More people would be able to take preventive health steps,” gynecologic oncologist Daniel Medina said.        

Study Details


With parents’ permission, researchers will vaccinate 20,000 adolescent women between the ages of 12 and 16 from several regions in the country. Those who are eligible will be asked to sign a document pledging to participate in monitoring every six months for four years. Parents also are required to sign a document providing authorization.


The study group will be divided into two parts. One group will receive two doses and the other will receive one. At the end of the trial, samples will be taken from participants to study the level of antibodies produced and whether any infection has occurred, González said.


Initial follow-up is programmed for four years because there will be a sufficient number of adolescents who will have initiated sexual activity,” González said.


If we discover that it works, we will follow [participants] for six more years. If we find that it does not protect them equally [which is unlikely given an abundance of evidence that suggests it will], we will administer a second dose,” she added.


Cervical lesions currently can only be detected by a Pap smear, an exam that women should get at least every two years, Porat said.


A More Accessible Vaccine


The study will be conducted with Harvard University so that their economic specialists can project how much money could be saved in the country from using a single-dose vaccine.


Initial results will be ready in four years and will be presented to agencies including the World Health Organization, the Pan-American Health Organization and Costa Rica’s Health Ministry. These institutions will provide recommendations on how to administer the vaccine based on study results.


The Bill and Melinda Gates Foundation and the National Cancer Institute are funding the project.


Why Guanacaste?


The agency, formerly known as Proyecto Epidemiológico Guanacaste (Guanacaste Epidemiological Project), began its research in the province in 1993. In 2014, it conducted a study that evaluated the vaccine’s efficacy on various strains of the virus (there are 13 strains in total).


This new study emerged from previous research that raised the question of whether a single dose of the vaccine would be sufficient.


Since then, the agency has studied cervical cancer and its link to HPV with the help of Guanacaste women. Some 55 collaborators work out of its office at Solarium, mostly from Guanacaste, González said.


The agency changed its name last year to work with a larger group starting this year, and its staff has tripled in size.