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Discovering the causes of cancer and the means of prevention

HPV Vaccine Trial in Costa Rica (CVT)

The HPV Vaccine Trial in Costa Rica (CVT) is a collaboration between investigators in Costa Rica and the National Cancer Institute. CVT was a blinded, randomized, phase III clinical trial of the bivalent HPV-16/18 virus-like particle (VLP) vaccine developed by investigators at NCI and other research institutions and manufactured by GlaxoSmithKline Biologicals. Its aims were to evaluate vaccine efficacy, immunological correlates of long-term vaccine success and failure, and other factors of immunological and etiological interest. The trial was initiated in June 2004 and enrollment of 7,466 women was completed in December 2005.

Trial staff followed enrolled women for a period of four years. Eligible participants were consented and randomized to receive three doses of the HPV 16/18 VLP or Havrix (Hepatitis A) vaccine over a period of six months. At entry and throughout follow-up, women were carefully monitored and received state-of-the-art screening for cervical neoplasia. 

In addition to strong evidence for vaccine safety and efficacy, data from the trial demonstrated that three doses of the HPV vaccine may not be necessary, as similar vaccine efficacy against cervical HPV 16/18 infection was observed among women who received two, and even a single dose, after four years of follow-up.

For more information, contact Aimée Kreimer, Ph.D.

Study Publications

Search all publications from the CVT study.

Requests for CVT Study Data

We encourage collaborations with outside researchers. Data requests undergo two reviews: completeness review by the coordinator managing requests, and suitability review by the principal investigators. To request an application and information packet, please contact the CVT coordinator at

Infections and Immunoepidemiology Branch - Research Areas