A research team from the University of Washington’s School of Medicine has noted that successful administration of the cervical cancer vaccine could potentially eliminate the disease worldwide.
How was this data on the cervical cancer vaccine collected?
A randomised and controlled trial of 2,275 women in Kenya revealed that a single dose of the cervical cancer vaccine – or the human papillomavirus (HPV) vaccine – was highly effective. The current procedure in place for women is a three-dose regimen.
“The single-dose efficacy was the same as multiple doses,” explained Dr Ruanne Barnabas, Principal Investigator in the trial.
Barnabas noted that the trial results could help the World Health Organization achieve its goal for 90% of 15-year-old girls to receive the cervical cancer vaccine by 2030 – currently, just 15% of women worldwide are vaccinated against cervical cancer.
Barnabas was a professor of Global Health at the University of Washington’s School of Medicine at the time of the study. She is now Chief of the Division of Infectious Diseases at Massachusetts General Hospital in Boston.
The results of this trial were published on Monday 11 April 2022 in the journal NEJM Evidence.
What do these findings suggest?
“These findings are a game-changer that may substantially reduce the incidence of HPV-attributable cervical cancer and positions single-dose HPV vaccination as a high-value and high-impact public health intervention that is within reach for us,” said Professor Sam Kariuki, Acting Director General at the Kenya Medical Research Institute.
“The findings add further support to the adoption of a single-dose cervical cancer vaccine, which could increase accessibility in low- and middle-income countries,” added Peter Dull, Deputy Director of Vaccine Development and Surveillance at the Bill and Melinda Gates Foundation, which funded the study.
“HPV vaccines are a powerful tool to reduce cervical cancer, but too many women and girls in low- and middle-income countries do not have access to them. The KEN-SHE study results contribute to a growing body of evidence supporting the potential for a single-dose HPV vaccination.”
How important is the distribution of this vaccine?
Most sexually active women and men will be infected with HPV at some point in their lives and some will be repeatedly infected. Thus, the peak time for acquiring the infection among both women and men is shortly after being sexually active.
While nine out of 10 HPV infections resolve on their own in two years, others lead to cancer of the reproductive system, mainly cervical cancer. HPV also can cause cancers of the cervix, vagina, vulva, penis, and oropharyngeal cancer (throat, tongue, and tonsils).
Currently, cervical cancer kills approximately one woman every two minutes worldwide. Most of those deaths are in Africa, which bears 80% of those diagnosed with cervical cancer. However, due to cost and limited vaccine supply, distribution of the cervical cancer vaccine has been low in areas with the highest burden of the disease.
How was this study conducted?
In the trial, women 15 to 20 years old were randomly assigned therapy and examined from December 2018 to June 2021. To be eligible, the women needed to be sexually active, have no more than five-lifetime partners, be HIV-negative, and have no history of the cervical cancer vaccine. A majority of those who enrolled (57%) were between 15 and 17 years old and most reported only one-lifetime sexual partner (61%).
The participants were randomised into three treatment arms:
- 760 received a bivalent vaccine that covered two strains of HPV (16/18), which represent 70% of cases;
- 758 received a nonavalent vaccine that covered seven strains of HPV (16/18/31/33/45/52/58), which represent 90% of cases; and
- 757 received a vaccine that protects against meningococcal meningitis.
What were the results?
After 18 months, the bivalent vaccine was 97.5% effective against HPV 16/18 and the nonavalent vaccine was 97.5% effective against HPV 16/18. The nonavalent vaccine was 89% effective against HPV 16/18/31/33/45/52/58. Even if women tested positive for one strain of HPV, the vaccine protected them from other strains of the virus.
Researchers noted that additional studies are required to test how long the cervical cancer vaccine lasts.
“This trial brings new energy to the elimination of cervical cancer. It brings great hope to the women living in countries like Kenya, who have a high burden of the disease,” noted Dr Nelly Mugo, Co-Principal Investigator of the study and Senior Principal Clinical Research Scientist with the Centre for Clinical Research at the Kenya Medical Research Institute in Nairobi. She also is a UW Associate Research Professor of Global Health.
Researchers said one impetus for the trial was the cervical cancer ward at the Kenyatta National Hospital in Nairobi. They said they want the ward empty.
“I believe that I will see cervical cancer eliminated in my lifetime,” concluded Dr Maricianah Onono at the Kenya Medical Research Institute. “So, let us do this – one-shot for every woman!”