What if, tomorrow, a single injection was enough to protect a teenager against the virus responsible for the majority of cervical cancers? A large clinical trial conducted in Costa Rica, ESCUDDO, has just delivered results that shake up the classic vaccination schedule against human papillomavirus, or HPV.
HPV is the most common sexually transmitted infection, and certain types, such as HPV16 and HPV18, cause most cervical cancers. Vaccines have been available for almost 20 years, but many young girls around the world remain unprotected. Detailed data of theESCUDDO testpublished in the New England Journal of Medicinerelaunch the debate on the single dose of HPV vaccine. The numbers speak for themselves.
One dose of HPV vaccine as effective as two according to the ESCUDDO trial
The ESCUDDO trial, launched in 2017 in Costa Rica, included 20,330 adolescent girls randomly assigned to four groups: one or two doses of a bivalent vaccine targeting HPV16 and HPV18, or one or two doses of a nonavalent vaccine covering HPV6, 11, 16, 18, 31, 33, 45, 52 and 58. The primary endpoint was based on the occurrence a new HPV16 or 18 infection between the 12th and 60th month after vaccination, persisting for at least six months. The statistical objective was to show that the one-dose strategy was not inferior to the two-dose strategy beyond a certain pre-defined difference threshold.
The authors also compared vaccinated participants to 3,005 unvaccinated girls and women aged 16 to 21, included in a parallel survey, whose baseline characteristics were similar. This analysis confirmed that vaccine effectiveness against persistent HPV16 or 18 infections reached at least 97% for all combinations of vaccine and number of doses. For the nonavalent vaccine, one dose was also found to be non-inferior to two doses in preventing all seven carcinogenic HPV types, with an observed difference of 0.56 infections per 100 participants (95% CI 0.01 to 1.11). For the investigators, a single injection therefore offered lasting protection comparable to that of the two-dose regimen.
The authors describe a result which constitutes “a finding that supports projections that a single dose will prevent most new infections and subsequent illnesses associated with these types“, wrote Aimée Kreimer and her colleagues at the National Cancer Institute in the New England Journal of Medicine.
What the single dose of HPV vaccine changes for the fight against cervical cancer
Beyond the figures, the authors emphasize public health issues. “High-coverage HPV vaccination is a pillar of efforts to combat cervical cancer, but to date, not even a third of eligible adolescent girls worldwide have received the vaccine, which has been authorized for almost 20 years“, recalled Aimée Kreimer and her colleagues. “Data from this trial support the WHO alternative recommendation for single-dose HPV vaccination to achieve higher coverage while maintaining sufficiently high efficacy“, they added.
In an editorial accompanying the publication, Ruanne V. Barnabas, of Massachusetts General Hospital and Harvard Medical School, points out that several works have “consistently shown that a single dose of HPV vaccine provides immunogenicity, efficacy, and durability of immune responses“. She believes that “This is encouraging news for global efforts to eliminate cervical cancer, the fourth most common cancer in women worldwide“and that”single-dose vaccination strengthens the vaccination pillar by simplifying delivery and reducing costs“. For her, “we have the evidence and the tools to eliminate cervical cancer. What remains is the collective will to implement them fairly, efficiently and now“.