Trials of one-dose schedules
The one-dose vaccine schedule has garnered a lot of interest, with several studies showing efficacy.
The KEN SHE trial, based in Kenya, showed that a single dose of the HPV vaccine was highly effective at preventing oncogenic infection, rivaling the protection offered by multidose regimens. Vaccine efficacy was 97.5% (P < .001) against HPV 16/18 for both the bivalent and monovalent vaccines, which is “comparable to that seen in multidose vaccine trials,” the researchers noted.
A study in India found that efficacy against persistent HPV 16 and 18 infection among participants evaluable for the endpoint was 95.4% for the single dose, 93.1% for the two-dose schedule, and 93.3% for the three-dose series.
Commenting on this trial in India in a recent interview with this news organization, Geoffroy Canlorbe, MD, PhD, of the department of gynecologic and breast surgery and oncology, Pitié-Salpêtrière Hospital, Paris, said the findings from India would need “to be confirmed by other studies.” The results were nonetheless “excellent news for developing countries where there are challenges when it comes to access to vaccination.”
Speaking at the 45th Congress of the French Society for Colposcopy and Cervical and Vaginal Diseases, he emphasized that at this stage, the findings “cannot be extrapolated” to France. HPV vaccination coverage is low in France (it is estimated that the rate is 23.7%, placing the country 28th of 31 countries in Europe), and he recommended continuing with the two- or three-dose schedule for the time being.
“This poor coverage has nothing to do with health care–related logistical or organizational issues; instead, it has to do with people’s mistrust when it comes to vaccination. Here, people who get the first dose get the subsequent ones,” said Dr. Canlorbe. “The very fact of getting two to three doses allows the person’s body to increase the production of antibodies and get a longer-lasting response to the vaccine.”
Ethics of the vaccine
In their editorial, Dr. D’Souza and Dr. Nderitu note that there are ethical considerations with the HPV vaccine that can “help guide deliberations, covering nonmaleficence, beneficence, health equity, stewardship, and solidarity.”
It would be inequitable and unjustifiable, they write, to offer a two-dose regimen to girls aged 9-14 years without also introducing multi-age cohort catch-up campaigns or programs for women who do not have access. “When it comes to an effective HPV vaccination schedule, no woman or girl should be left behind,” they say.
To achieve the goal of eliminating cervical cancer, “countries must ensure that 90% of girls are vaccinated, 70% of women are screened, and 90% of women with precancerous lesions receive treatment and care,” they write. “Given resource constraints, particularly in low-middle income countries, policy makers have a responsibility to ensure that resources are used in an optimal manner that promotes the right to health of all individuals.”
Thus, countries that are lagging far behind in cervical cancer education, screening, and treatment should consider opting for a one-dose regimen for girls aged 9-14 years, as well as using additional resources to close the gap in these other areas.
Dr. Markman has relationships with Genentech, AstraZeneca, Celgene, Clovis, and Amgen; he is also a regular contributor to Medscape Oncology with the Markamn on Oncology video column. Dr. D’Souza and Dr. Nderitu have disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.