Vaccination against the human papillomavirus (HPV) can significantly reduce levels of oral HPV infection, according to new unpublished research.
A study found that young adults in the US who hadn’t been vaccinated were around 14 times more likely to have oral HPV infections than those who were vaccinated.
Experts said the findings suggest that vaccination could prevent certain head and neck cancers caused by the virus.
Though most of the hundreds of kinds of HPV are harmless, around 12 types can cause cancer.
HPV infection is linked to almost all cases of cervical cancer diagnosed in the UK. Since 2008, girls aged 12-13 in the UK have been offered a vaccination against the 2 most common ‘high-risk’ types of HPV.
Professor Richard Shaw, Cancer Research UK scientist at the University of Liverpool, said that while there has been much debate in the UK about vaccinating both boys and girls against HPV, the latest study around oral infection supports the case for vaccinating both.
Levels of oral cancers caused by HPV have risen in recent decades among US men, and Dr Maura Gillison, who led the study at Ohio State University, said that the HPV vaccine is one of the most important advances in cancer prevention in the last few decades.
The research, to be presented at the upcoming 2017 ASCO Annual Meeting in Chicago, compared HPV infection rates between young adults (aged 18-33) in the US who had received 1 or more doses of a HPV vaccine to those who had not.
This included 2,627 young adults from the US National Health and Nutrition Examination Survey, from 2011-2014.
The researchers looked for infection with 4 types of HPV (HPV 16, 18, 6 and 11). These were the types covered by HPV vaccines offered before 2016 in the US, and are the types covered currently by the vaccination programme for girls in the UK.
They found that levels of infection with those types of HPV were lower among those who reported receiving at least 1 vaccine dose (0.11%) than among those who were not vaccinated (1.61%).
But levels of oral infection with those HPV types not covered by the vaccine was similar for the 2 groups, suggesting the vaccine was having the desired effect.
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The researchers also found that fewer than 20 in 100 young adults reported receiving at least 1 dose of the HPV vaccine before they were 26. The vaccination rate was much lower among men than women, with 7 in 100 men vaccinated compared to 30 in 100 women.
If uptake is high, vaccination programmes can protect people who haven’t received the vaccine. This idea of ‘herd protection’ means that the greater the number of people vaccinated against HPV, the lower the risk of any one person coming into contact with the virus.
But Gillison said that while the impact on vaccinated individuals was positive, the overall population-level benefit was lower than hoped in men due to low vaccine uptake.
The researchers estimated that the levels of oral infection of HPV types covered by the vaccination were reduced in the general population by 17% overall, and by 25% in women, and by about 7% in men.
“The HPV vaccine has the potential to be one of the most significant cancer prevention tools ever developed, and it’s already reducing the world’s burden of cervical cancers,” said Dr Bruce Johnson, ASCO’s president-elect.
“The hope is that vaccination will also curb rising rates of HPV-related oral and genital cancers, which are hard to treat. This study confirms that the HPV vaccine can prevent oral HPV infections, but we know it only works if it’s used.”
Shaw added that the number of head and neck cancers is on the rise in the UK, likely caused by a combination factors, including HPV infection. “Along with vaccinating against HPV, helping people to quit smoking and cut down on alcohol are important,” he said.
“If caught at an early stage, treatment is more likely to be successful. It’s important to get to know your body and what’s normal for you, and if you notice anything unusual, see your GP.
Gillison, M. L. et al. (2017) Impact of prophylactic human papillomavirus (HPV) vaccination on oral HPV infections among young adults in the U.S. 2017 ASCO Annual Meeting