Single-dose HPV shot grants women improved chances of avoiding cervical cancer

Women have a better shot at avoiding cervical cancer thanks to the single-dose human papillomavirus (HPV) vaccination, which has now been approved in South Africa.

The much-anticipated transition from the current two-vaccination strategy aligns with recent evidence-based World Health Organisation (WHO) recommendations.

Health experts who participated in a recent “Women Up To Know Good” webinar, titled “HPV at your cervix” emphasised the effectiveness and affordability of the single-dose strategy in low- and middle-income countries.

HPV vaccinations are the most effective available tool for preventing cervical cancer. Usually administered to girls under the age of 15, the vaccine triggers an immune response that later protects against strains of HPV — the virus responsible for the development of virtually all cervical cancer cases.  

A comprehensive rollout of the single-dose vaccine is one part of a multifaceted approach to eliminating cervical cancer in Africa.

To eliminate cervical cancer globally, the WHO set the following goals for 2030:

• 90% of girls vaccinated by age 15;
• 70% of women screened for HPV (by a high-performance test) by age 35, and again at 45; and
• 90% of women with cervical cancer receiving treatment.

However, resource constraints have seen low- and middle-income countries moving slowly to reach these targets.

The success of South Africa’s school-based programme, initiated in 2014, illustrates how targeted interventions can help low- and middle-income countries (LMICs) to reach vaccination targets.

Clearing cost hurdles

At the GIFT webinar, leading cervical cancer expert Prof Lynette Denny of the University of Cape Town, Dr Zizipho Mbulawa of the National Health Laboratory Services and Walter Sisulu University, and physician scientist Dr Ruanne Barnabas of Harvard University discussed ways of increasing the accessibility and uptake of vaccinations and cervical cancer screenings.

Barnabas shared findings from research she and her colleagues conducted in Kenya that provided the evidence for the WHO policy change, recommending the one-dose vaccine. The study showed a 98% vaccine efficacy against HPV 16/18 — the strains that are most strongly linked to cervical cancer.

“After three years, single-dose HPV vaccine efficacy remained high and durable,” Barnabas said, adding that the vaccine also provided protection against other HPV strains.

She and her team found that the rollout of the single-dose vaccine in Kenya, in place of the two-dose strategy, would save the country $100m (R1.9bn).

What about the costs associated with secondary prevention and treatment — the second and third WHO pillars of cancer elimination?

Cervical cancer screening has also historically been challenging for resource constrained countries, said Denny.

To screen for cervical cancer, a healthcare provider traditionally takes a pap smear of cervical cells, which are sent to a laboratory to be assessed for any abnormalities that could lead to cancer.

If the test, known as cytology, comes back positive, the woman is referred for a colposcopy (in which a doctor uses a specialised instrument to examine cervical tissues), to confirm the presence of precancerous cells.

The entire process requires laboratories, trained technicians and healthcare providers, and a functional referral system — resources that LMICs don’t always have, she said.

Missing links in this screening-to-treatment process mean that many pre-cancer cases fall through the cracks. Denny is involved in research exploring alternatives less and resource-intensive screening methods.

The most effective and popular is molecular testing using nucleic acid amplification tips, or NAATS (nucleic acid amplification tests), she said. Instead of testing for abnormal cells, this method tests for the presence of HPV DNA.

The NAAT replicates any HPV present in a sample of cervical cells, making the virus easier to detect.

“Using HPV NAATs as the primary screening test prevents more cervical cancers and saves more lives than ... cytology as the primary screening test,” Denny said.

In contexts where the necessary infrastructure is absent, visual assessments can be used for preliminary screening, she said, with positive cases then referred for NAATs.

One-day screening and treatment

The finding comes from a 2023 study that Denny and her team conducted in Khayelitsha, outside Cape Town. In that study, the researchers screened 3,062 women using on-site NAATs. They found that the test successfully detected 99% of high-risk HPV types.

The advantage of NAATS, as Denny demonstrated, is that it can take place during a single clinic visit, at a single location. This also means that women can often be treated on the same day, reducing the number of people who fail to return for their test results and never receive treatment.    

In total, 28% of women at the Khayelitsha site tested positive for high-risk HPV (41.1% of women were living with HIV and 17.4% without HIV).

The research team treated the women who tested positive with thermal ablation (a standard, low-discomfort procedure in which a healthcare practitioner uses a heated metal probe to destroy precancerous cells in the cervix).

One year later, Denny and her team wanted to find out if the women who had been treated were still clear of high-risk HPV.  They tested them again and found that 65% of women without HIV had no HPV, and 40% of women living with HIV had cleared all HPV. No new cervical cancer cases were found.

Room for HPV treatment improvement?

Though undoubtedly more women received potentially life-saving treatment than if they’d been screened using the traditional pap test, Denny notes that the study showed that the thermal ablation was only moderately successful in eliminating the high-risk HPV.

“The literature is conflicted, [with] some reporting high rates of HPV clearance, [and] others, like us, reporting low rates of clearance post-ablation,” she said, adding that research is needed to identify predictors of ablation treatment failure.

Additionally, other, supplementary treatments — such as therapeutic vaccinations — may be needed going forward. However, before vaccinations and screening can even take place, another hurdle must be overcome.

Increasing knowledge of HPV

In South Africa, low knowledge and awareness about HPV and cervical cancer hinders effective screening and vaccination efforts, especially in rural areas.

Dr Mbulawa shared her recent research illustrating the importance of educational programmes in cervical cancer elimination efforts. Though clinics in areas like the OR Tambo district municipality in the Eastern Cape offer pap smears, uptake is very low, she said.

She and her colleagues conducted research in 11 rural communities in the Eastern Cape to assess public knowledge of HPV.  They found that only 26% of those who participated had a good knowledge of cervical cancer (defined as scoring at least 65% in a cervical cancer quiz). And, of those with good knowledge, 84% were women.

This lack of knowledge matters for vaccination coverage, said Mbulawa, because children require their parents’ consent to receive HPV vaccinations. And it matters for screening and treatment too, because women often rely on partners and fathers for financial support to access healthcare services.

To assess the potential impact of HPV education, Mbulawa’s team paid a visit to high schools, where they provided students with one-off HPV education sessions in life orientation class.

Before the HPV class, virtually none of the student participants (0.83%) had good knowledge of HPV and cervical cancer. After the class, 74% of students displayed good knowledge, scoring at least 50% in the HPV test.

Given the significant improvement after a single information session, the findings show the potential for continuous HPV education to dramatically increase knowledge of cervical cancer prevention, Mbulawa said.

Her research also involved providing women at clinics with information about HPV.

“No woman will go for cervical screening if they don’t have good knowledge about it. No-one will agree to ... testing in our rural areas,” she said. “No-one will consent for their children to be vaccinated because the knowledge is not there.”

Barnabas emphasised the need to start thinking differently about cervical cancer prevention to accelerate progress towards the WHO goals. She noted that those so-called catch-up vaccines, administered to older girls and young women, can still be effective, and also recommended extending the HPV vaccination to boys.

In her closing remarks, Denny quoted gynaecologist Prof Mahmoud Fathallah to underscore the need for government prioritisation: “Women are not dying because of diseases we cannot treat. They are dying because societies have yet to make the decision that their lives are worth saving.”

Watch the Women up to Know Good webinar hosted by the GIFT (Genital Inflammation Test) team at the University of Cape Town here.