The challenges of immunobridging without established correlates of vaccine-induced protection
Mené au Costa Rica sur 620 filles (9-14 ans) et 620 femmes (18-25 ans) ayant reçu leur premier vaccin contre le papillomavirus humain (HPV), cet essai évalue la non-infériorité, du point de vue de la réponse immunitaire, d'une dose unique de vaccin bivalent anti-HPV chez les jeunes filles par rapport à trois doses du vaccin quadrivalent anti-HPV chez les femmes
Cervical cancer remains one of the top causes of cancer-associated morbidity and mortality among women in low-income and middle-income countries (LMICs), despite effective primary and secondary prevention methods being well known for more than a decade.1 In 2022, the Global Cancer Observatory reported 662 301 cases of cervical cancer and 348 874 cervical cancer-associated deaths worldwide, corresponding to an age-standardised incidence of 14 cases of cervical cancer per 100 000 women globally.2 This incidence is a far cry from WHO's elimination goal of fewer than four cervical cancer cases per 100 000 women.3 The implementation of human papillomavirus (HPV) vaccination has been hampered in many countries by a previous shortage of available vaccine doses, high costs, and logistical challenges of implementing a multidose vaccine regimen. These challenges have disproportionately affected LMICs where the incidence of cervical cancer is highest.4
Early results from the Costa Rica HPV Vaccine Trial (CVT)5 and the International Agency for Research on Cancer (IARC) India trial6 showed that vaccine efficacy in participants who received one dose of the HPV vaccine was similar to that in participants who received two or three vaccine doses. This finding caused a major change in thinking for subunit vaccines, which were traditionally thought to require a prime–boost vaccination strategy to provide protection. Long-term follow-up of the same trials estimated that single-dose bivalent vaccine efficacy against prevalent HPV-16 and HPV-18 infection was 82% (CVT)5 and single-dose quadrivalent vaccine efficacy against persistent HPV-16 and HPV-18 infection was as high as 92% (IARC India trial).6 With these hopeful findings, and under the backdrop of HPV vaccine shortages, in 2022 the Strategic Advisory Group of Experts on Immunization endorsed an alternative one-dose strategy for girls aged 9–20 years. To date, several countries have implemented an HPV vaccination programme with one dose (eg, Nigeria), and several other countries with established programmes have switched from a two-dose to a one-dose vaccination schedule (eg, the UK). However, there remains concern regarding the long-term efficacy of one-dose vaccination schedules.
The Lancet Infectious Diseases , commentaire en libre accès, 2025