HPV vaccines have been authorised in the European Union since 2006.
A single HPV vaccination appears just as effective as two doses at preventing the viral infection that causes cervical cancer, researchers reported on Wednesday.
HPV, or human papillomavirus, is very common and spread through sex. Most HPV infections clear up on their own, but some linger, causing cancers that appear years later, including cervical cancer in women and rarer cancers in both women and men.
HPV vaccines have been authorised in the European Union since 2006. Countries that adopted the jab early on have already reported a drop in precancerous cervical lesions.
But cervical cancer still kills about 340,000 women worldwide annually – and the new findings from a huge study in Costa Rica could help spur global efforts to protect more girls and young women in harder-to-reach low-income countries.
The study enrolled more than 20,000 girls between the ages of 12 and 16. Researchers tested two different HPV vaccines used around the world, giving half the girls one shot type and the rest the other.
Then six months later, half of the girls got a second dose of their assigned vaccine, while the rest instead received an unrelated child vaccination.
They all were tracked for five years, receiving regular cervical tests for the most cancer-prone HPV strains. Infection rates were compared to a separate unvaccinated group.
A single HPV shot provided about 97 per cent protection, similar to two doses, according to the study, which was published in the New England Journal of Medicine.
Previous studies had suggested one dose could work well, but the new findings confirm strong protection for at least five years, Dr Ruanne Barnabas, an infectious disease specialist at Massachusetts General Hospital in the United States, wrote in an accompanying editorial.
“We have the evidence and tools to eliminate cervical cancer. What remains is the collective will to implement them equitably, effectively, and now,” wrote Barnabas, who wasn’t involved in the Costa Rican study.
Most EU countries recommend two HPV shots starting between the ages of 9 to 12 for most girls and boys, as the virus also can cause head-and-neck and other cancers. Catch-up shots are recommended for anyone in their 20s who hasn't been vaccinated.
Over the past decade, HPV vaccination rates have risen steadily in countries like Spain and Germany, but fallen in the United Kingdom and Italy, according to data from the World Health Organization (WHO).
Globally, the agency estimates less than a third of adolescent girls have been vaccinated.
The new study offered no information about HPV-related cancers beyond the cervix, and the researchers cautioned that longer monitoring is needed.
