Health experts have urged the government to expand protection through the 9-valent human papillomavirus (HPV) vaccine after a new study found a shift in the dominant high-risk HPV strain affecting Filipino women, with HPV-52 emerging as the most prevalent instead of the previously assumed HPV-16 or HPV-18.

The findings, presented during the Philippine National Cancer Summit (PNCS), come from the DEFEAT HPV Study conducted by the University of the Philippines (UP) National Institutes of Health (NIH) and funded by the Department of Science and Technology (DOST).

Led by Dr. Sheriah Laine de Paz-Silava of the UP Manila College of Medicine, the research is described as the most comprehensive community-based HPV study in the country since the 1990s.

“We expected that type 16 and 18 would be most common,” she said.

“But we saw that type 52 was the most common detected genotype. This is consistent with the epidemiology in Asia,” she went on.

Silava said the study enrolled nearly 1,200 women from urban Manila and rural Cavite and found that about 11 percent were infected with high-risk HPV, with urban participants facing a 1.62 times higher risk of infection.

“We saw a prevalence of 11% [caused by various HPV types], and we think that the nonavalent vaccine might be beneficial for the Philippines,” Silava said.

The research showed that only 23.9 percent of infections involved HPV-16 or HPV-18- - -types covered by earlier-generation vaccines- - -while 53.7 percent involved genotypes included in the 9-valent vaccine, including HPV-52.

Experts said this indicates that more than half of high-risk infections detected in the study communities could potentially be prevented with broader vaccine coverage.

“When we talk about cervical cancer, it’s an infectious kind of cancer. HPV is the necessary cause,” said Silava. “… and because cervical cancer is infectious, elimination is possible.”

According to Globocan 2022 data, cervical cancer remains the second most common cancer among Filipino women, with around 8,000 new cases and 4,000 deaths annually.

“With over half of infections linked to genotypes included in the nonavalent HPV vaccine, the findings provide local evidence supporting serious consideration of expanded vaccine coverage,” Silava noted.

Silava said that less than two percent of the women included in the study were vaccinated, adding that screening uptake remains incredibly low, particularly in rural areas.

Currently, the National Immunization Program provides public school girls aged 9 to 14 with a four-valent HPV vaccine.

On the other hand, the nonavalent HPV vaccine is available locally but must undergo evaluation by the DOST-Health Technology Assessment Council before inclusion in the Philippine National Formulary and consideration for the government vaccination program.