Today, the World Health Organization’s (WHO) Strategic Advisory Group of Experts (SAGE) on Immunization concluded that a single dose of human papillomavirus (HPV) vaccine delivers solid protection against HPV. Based on the available evidence, SAGE advised that countries may now choose between a one- or two-dose schedule for 9–14-year-old girls and women aged 15 to 20. This is a major step toward reaching the WHO’s global strategy to accelerate the elimination of cervical cancer. One target outlined in the strategy is by year 2030 for 90% of girls to be fully vaccinated with HPV vaccine by age 15 years. With 2021 global coverage at just 13%, this new SAGE recommendation could help make WHO’s elimination goals achievable.
About 90% of cervical cancer deaths occur in low-and middle-income (LMIC) countries. And although women in LMICs bear a disproportionately large cervical cancer burden, vaccination rates are 40% lower in LMICs than the rest of the world largely due to financial and logistical barriers. Many country programs struggle to achieve high coverage with two-dose HPV vaccine schedules and countries that self-finance are reluctant to introduce a comparatively expensive vaccine. In recent years, HPV vaccine supply constraints and impacts from the COVID-19 pandemic have also impeded widespread coverage and introduction. A single-dose HPV vaccination program has the potential to accelerate introduction for countries that have yet to introduce the vaccine and facilitate new options for current national programs by simplifying delivery and lowering program costs.
Evidence on single-dose HPV vaccination
Over the last four years, the Single-Dose HPV Vaccine Evaluation Consortium, coordinated by PATH, has gathered and evaluated data from clinical trials, observational studies and modeling analyses regarding the value of a single-dose HPV vaccination schedule.
Results are emerging from several clinical trials that have been evaluating a single dose of HPV vaccine. In Kenya, a randomized controlled clinical trial demonstrated that a single dose of HPV vaccine was about 98 percent effective in preventing persistent HPV infections caused by HPV-16/18, the most common HPV types responsible for 70% of cervical cancers. Two high-quality observational studies in India and Costa Rica show protection against HPV infections after a single dose to be similar to two or three doses and last up to at least 10 years after vaccination. Another study in Tanzania showed that efficacy in young girls ages 9-14 years can be inferred based on bridging the immune response to studies conducted in India and Costa Rica. A single-dose HPV vaccination schedule is further supported by model-based evidence which consistently shows that single-dose vaccination, in settings that have not yet introduced HPV vaccines, will lead to substantial reduction in cervical cancer cases. Additionally, reaching more girls with a single dose will avert many more cervical cancer cases than vaccinating fewer girls with a second dose.
After review and evaluation by the Consortium, the current evidence supports the conclusion that single-dose HPV vaccination of the bivalent (Cervarix®), quadrivalent (Gardasil®), and nonavalent (Gardasil® 9) vaccines gives equivalent or near-equivalent protection to two-dose vaccination. The data accumulated to date and SAGE’s recent recommendation is promising for countries that have yet to introduce or are struggling to reach all eligible populations. With greatly reduced costs for vaccine supply and delivery and simplified implementation potentially allowing more countries to introduce HPV vaccination or increase uptake, single-dose HPV vaccination could substantially reduce the incidence of HPV-attributable cervical precancer and cancer.
Reaching every girl with HPV vaccine
Since their introduction in 2006, HPV vaccines have been shown to significantly reduce vaccine-type HPV infections and precancerous cervical lesions. Data accumulated to date on single-dose HPV vaccination provide strong evidence that a single-dose schedule could have a similar impact.
These findings are particularly relevant as HPV vaccine programs face increased challenges with vaccine accessibility and delivery due to the COVID-19 pandemic and recent vaccine shortages. For countries impacted by these issues, these findings provide reassurance that administration of a single dose will have a positive public health benefit while alleviating financial and logistical barriers.
In mid-2022, the Consortium will release its fourth edition of the Review of the current published evidence on single-dose HPV vaccination. This comprehensive review and assessment is compiled by leading researchers and experts to inform global, regional, and national HPV vaccine schedule policies and vaccine delivery programs. The review includes current published evidence from clinical trials, immunogenicity studies, other observational studies, and impact modeling.
For more information
Subscribe to the HPVflash newsletter, for more updates on the evidence as it becomes available. The Consortium will release a fourth edition of the evidence review by mid 2022.
Learn more in the review and summaries: