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Ruanne Barnabas, MD, chief of the Division of Infectious Diseases in the Department of Medicine at Massachusetts General Hospital and professor of Medicine at Harvard Medical School, is the senior author of a recent abstract presented at International Papillomavirus Conference, A Randomized Trial of Single-Dose HPV Vaccination Efficacy Among Young Women: Final Efficacy Results.

What was the question you set out to answer with this study?

What is the vaccine efficacy of a single dose of either licensed vaccine for human papillomavirus (HPV)?

What Methods or Approach Did You Use?

Our team in Kenya conducted a randomized, multicenter, double-blind, controlled trial to investigate the efficacy of a single dose of HPV vaccines in young women.

We enrolled 2,275 participants between the ages of 15-20 and randomly assigned them to receive either the bivalent HPV or nonavalent HPV or meningococcal vaccine.

During follow-up, clinicians collected cervical swabs every six months, which were tested for HPV DNA for endpoints. The outcome was incident persistent vaccine type-specific HPV infection. We analyzed vaccine efficacy (VE) up to the cross-over study visit at month 36.

What Did You Find?

The results showed that the single dose of both the bivalent and nonavalent HPV vaccines were highly efficacious, with a vaccine efficacy of 98%. Additionally, the nonavalent vaccine had a vaccine efficacy of 96% for the nine types of HPV it targets.

What are the Implications?

This study provides important evidence that a single dose of HPV vaccine can be highly effective in preventing persistent infections, and ultimately, cervical cancer.

Overall, we are proud to have contributed to advancing knowledge about HPV vaccination and its potential to prevent cervical cancer.

From our initial 18-month data, there have been concerns raised regarding the durability of the single dose HPV vaccine. This 36-month data helps to allay this anxiety. We encourage health ministers particularly those in low and middle income countries, to consider the findings of the KEN SHE Study and to work towards increasing access to the HPV vaccine, including the single dose option where appropriate

Maricianah Onono, MD, PhD
KEN SHE Country Director

We believe that these findings could have significant implications for vaccination programs in low-resource settings, where the burden of cervical cancer is highest.

Nelly Mugo, MD, MPH
Kenya Research Institute


The study was funded by the Bill and Melinda Gates Foundation and conducted by KEMRI in collaboration with the Kenyan Ministry of Health.

Following the WHO recommendation in support of a one-dose regimen for HPV vaccine could help make the vaccine more accessible to women and girls around the world by lowering costs, alleviating pressure on supply, and making the vaccine easier to deliver.

Peter Dull
Deputy Director, Vaccine Development & Surveillance
Gates Foundation

About the Massachusetts General Hospital

Massachusetts General Hospital, founded in 1811, is the original and largest teaching hospital of Harvard Medical School. The Mass General Research Institute conducts the largest hospital-based research program in the nation, with annual research operations of more than $1 billion and comprises more than 9,500 researchers working across more than 30 institutes, centers and departments. In July 2022, Mass General was named #8 in the U.S. News & World Report list of "America’s Best Hospitals." MGH is a founding member of the Mass General Brigham healthcare system.