The results from a recent trial support the WHO recommendation for single-dose human papillomavirus (HPV) vaccination to achieve higher coverage while sustaining efficiency, say researchers in Costa Rica.
One dose of a bivalent or nonavalent vaccine was non-inferior to two doses, their randomised ESCUDDO trial found, with effectiveness being at least 97% against HPV16 or 18 infection, no matter whether a participant received one or two doses, reports Medpage Today.
Among more than 20 000 girls aged 12 to 16 in Costa Rica, the rate difference between one and two doses of the bivalent vaccine was -0.13 infections per 100 participants (95% CI -0.45 to 0.15, P<0.001 for non-inferiority), and this difference for the nonavalent vaccine was 0.21 infections per 100 participants (95% CI -0.09 to 0.51, P<0.001 for non-inferiority), reported Aimée Kreimer, PhD, of the National Cancer Institute, and colleagues.
Vaccine effectiveness was at least 97% against infection with HPV16 or HPV18 – the genotypes accounting for most cervical cancers – regardless of whether a participant was given one or two doses of the bivalent or nonavalent HPV vaccine, “a finding that supports projections that a single dose will prevent most new infections and subsequent disease associated with these types”, the authors wrote in The New England Journal of Medicine.
These results follow two recent large meta-analyses that showed that HPV vaccination in girls aged 16 and younger was safe and substantially reduced the risk of developing cervical cancer.
“High-coverage HPV vaccination is a mainstay of cervical cancer control efforts, but to date not even one third of eligible adolescent girls worldwide have received the vaccine, which has been licensed for almost 20 years,” Kreimer and colleagues noted.
“The evidence from this trial supports the WHO alternative recommendation for single-dose HPV vaccination to achieve higher coverage while maintaining sufficiently high efficacy.”
In an accompanying editorial, Ruanne Barnabas, MBChB, DPhil, of Massachusetts General Hospital and Harvard Medical School in Boston, noted that multiple studies have “consistently shown that a single dose of HPV vaccine provides immunogenicity, efficacy, and durability of immune responses”.
“This is encouraging news for global efforts to eliminate cervical cancer, the fourth most common cancer among women worldwide,” she wrote. “One-dose vaccination strengthens the vaccination pillar by simplifying delivery and reducing costs.
“We have the evidence and tools to eliminate cervical cancer. What remains is the collective will to implement them equitably, effectively, and now.”
The ESCUDDO trial was launched in 2017 and included 20 330 girls aged 12 to 16 who were randomised in a 1:1:1:1 ratio to receive one or two doses of a bivalent HPV vaccine (HPV16 and HPV18) or one or two doses of a nonavalent HPV vaccine (HPV6, HPV11, HPV16, HPV18, HPV31, HPV33, HPV45, HPV52, and HPV58).
Preliminary results were presented earlier this year at the American Association for Cancer Research annual meeting.
The primary endpoint was new HPV16 or 18 infection occurring from month 12 to month 60 and persisting for at least six months. The pre-specified non-inferiority margin was 1.25 infections per 100 participants.
Kreimer and colleagues also found that one dose of the nonavalent vaccine was non-inferior to two doses in preventing against any of the seven carcinogenic HPV types – HPV16, 18, 31, 33, 45, 52, or 58 – with an observed rate difference of 0.56 infections per 100 participants (95% CI 0.01-1.11, P<0.001).
To assess effectiveness, Kreimer and colleagues compared HPV16 or HPV18 infection among the trial participants with that among 3 005 unvaccinated girls and women ages 16 to 21 enrolled in a non-randomised survey. The characteristics of the survey participants were similar to those of the trial participants.
With respect to the effectiveness in preventing HPV16 or HPV18 infection that persisted for at least six months, the effectiveness with one or two doses of the bivalent jab was 98.2% and 97.8%, respectively, while the effectiveness with one or two doses of the nonavalent vaccine was 97% and 98.5%.
The effectiveness of the nonavalent vaccine against persistent HPV infection with any of the seven carcinogenic HPV types included in the nonavalent vaccine formulation was 94.5% with one dose and 95.8% with two doses.
The effectiveness of one and two doses against all the individual HPV types included in the nonavalent vaccine formulation was at least 90%, with the exception of HPV11.
Serious adverse events that were considered by the investigators to be “possibly, probably, or definitely related to HPV vaccination” occurred in seven participants over a period of five years.
Medpage Today article – One Dose of HPV Vaccine Just as Effective as Two, Trial Finds (Open access)
See more from MedicalBrief archives:
Just one dose of the HPV vaccine found to be effective
HPV one-dose jab campaign to now include private schools
SA makes strides with HPV vaccine campaign, but not fast enough
HPV vaccine cuts cervical cancer by nearly 90% — UK population registry study
HPV vaccine significantly lowers infection rates in teen girls — CDC study