Single Dose of HPV-16/18 Vaccine May Prevent Cervical Cancer
A single dose of the recombinant human papillomavirus (HPV) bivalent (types 16 and 18) vaccine (Cervarix) appears to be as effective in preventing certain HPV infections as three doses, the currently recommended course of vaccination, concluded a study published by Kreimer et al in The Lancet Oncology.
In the study, data from two large trials of the HPV-16/18 vaccine were analyzed to compare the effectiveness of one, two, or three doses of the vaccine in preventing HPV infection. In the trials, women were randomly assigned to receive three doses of HPV-16/18 vaccine or a control vaccine. Although a number of the women received fewer than the three doses, follow-up tests were completed to evaluate the effectiveness of the vaccine in all the women for a period of 4 years.
Study Findings
The analysis determined the protection from one dose is similar to that achieved by three doses of the vaccine.
“These exciting findings address the fact that nearly two-thirds of people who get HPV vaccines do not get all three doses in a timely manner,” said Diane Harper, MD, PhD, the Rowntree Endowed Chair and Professor in the Department of Family and Geriatric Medicine at the University of Louisville School of Medicine, and a principal investigator in one of the trials included in the analysis. “Knowing that [HPV-16/18 vaccine] offers protection in one dose reassures public health agencies that they are not wasting money when most of their vaccines are given to those who never complete the three-dose series.”
She added, “Kentucky is one of the states that has not had a program in place to make [HPV-16/18 vaccine] available to all of its citizens and has very low three-dose completion rates of [HPV quadrivalent (types 6, 11, 16, 18) vaccine (Gardasil)],” said Dr. Harper.
Other HPV Vaccines
In their published report, the study authors noted, “We deemed trials of the quadrivalent and nonavalent [Gardasil 9] HPV vaccines out of the scope of this work because it is currently unknown whether it is the virus-like particle that induces the strong immune response, in which case both vaccines may be efficacious with a single dose, or whether the special adjuvant of the HPV-16/18 vaccine is the cause of one-dose efficacy. Moreover, differences existed in the trial designs between the HPV-16/18 vaccine programmes and the quadrivalent or nonavalent programme—eg, in inclusion criteria, assays for HPV DNA and serology, and colposcopy algorithms. Consequently, we focused on only the HPV-16/18 vaccine.”
HPV types 16 and 18 are responsible for about 70% of cervical cancers worldwide. These and other types of HPV cause the cancer precursor cervical intraepithelial neoplasia grade 3 (CIN 3).
“From all studies done, [HPV-16/18 vaccine] protects against CIN 3 caused by all HPV types at 93% efficacy,” Dr. Harper said.
Aimeé R. Kreimer, PhD, of the National Cancer Institute, is the corresponding author for The Lancet Oncology article.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
