Single-dose HPV vaccine could be effective for preventing cervical cancer

A single dose of human papillomavirus (HPV) vaccine could be effective for preventing cervical cancer, raising hopes of fighting the disease in Sub-Saharan Africa, a conference has heard.

Cervical cancer is ranked the fourth most common cancer among women globally, with up to 90 per cent of deaths occurring in low- and middle-income countries, according to a 2018 World Health Organization (WHO) report.

About 99 per cent of cervical cancer cases are associated with infection with human papillomaviruses (HPV) through sexual contact.

Cervical cancer occurs in the cells of the cervix — the lower part of the uterus that connects to the vagina.

Health experts say that although cervical cancer is preventable, low uptake of the HPV vaccine in low- and middle-income countries (LMICs) is a challenge.

In LMICs, low vaccine coverage is due, in part, to the cost and logistics of reaching girls with a standard multi-dose vaccine schedule."

Maricianah Onono, senior principal clinical research scientist at the Kenya Medical Research Institute and co-author of the study

Researchers presented the results of the study during the 34th International Papillomavirus Conference in Canada this month.

Researchers randomly selected adolescent girls and young women into three groups in Kenya, with 760 receiving a single-dose HPV vaccine that covered two strains of HPV, 758 receiving a single dose that covered seven strains of HPV and 757 being given a vaccine for protection against meningococcal meningitis.

The study, which began in December 2018, involved assessing whether a single dose of the HPV vaccine could be effective as the current three-dose regimen for girls and young women.

After 18 months, the HPV vaccine was found to be 97.5 per cent effective against HPV whereas the other single-dose vaccine was 89 per cent effective against HPV.

"Our data covers 18-24 months [and] we hope to follow up these girls for up to 60 months to answer the question of durability," according to Onono.

Onono tells SciDev.Net that even though vaccination guidelines recommend multi-dose strategies, the single dose HPV vaccine effectiveness is equivalent to the standard two dose- or three-dose regimens given to girls 14 years and below and 15 years and above respectively.

Onono says that the single dose vaccine will be able to simplify logistics and costs of delivery of the HPV vaccine and calls for health policymakers to increase the availability of the vaccine to accelerate elimination of cervical cancer.

"At the population level, increasing vaccine coverage increases effectiveness; vaccination of multi-age adolescent cohorts (nine to 14 years) with catch-up vaccination (to age 26 years) doubles the prevention of HPV-associated precancerous lesions," Onono explains.

Stanley Aruyaru, director of medical services at Kenya's St. Teresa Mission Hospital in Meru, says that a shift to a single vaccine dose will have huge cost-saving benefits.

"This study has showed that just one dose is as good as multiple doses. This will cut the costs by half and abolish the logistics that impede uptake of the multiple doses," explains Aruyaru.

He adds: "With the promising trials and findings of this study, there is hope. The future in terms of vaccine coverage for prevention of cervical cancer will be good."