The HPV vaccine is driving down oral infection rates and moving the US closer towards ‘herd immunity’, a new study suggests.
Researchers found that, between 2009 and 2016, oral HPV infections among unvaccinated men fell by about 40 percent.
The team, from the MD Anderson Cancer Center in Houston, Texas, says they believe men are becoming further protected from becoming infected – even if they haven’t received the jab – because HPV vaccination rates are rising among women.
They add that not only are the findings encouraging because rates of the sexually-transmitted infection (STI) are falling, but that this will likely lead to fewer cancer diagnoses every year.
A new study from the MD Anderson Cancer Center in Houston, Texas, says that unvaccinated men are being protected by ‘herd immunity’ because rates of HPV vaccination in women are rising (file image)
HPV, short for Human papillomavirus, is the most common STI in the US, affecting around 79 million people.
It has been linked to numerous cancers – including prostate, throat, head and neck, rectal and cervical cancer.
Since the HPV vaccine was introduced in 2006, 79 countries and territories have implemented publicly funded national HPV vaccination programs.
In the US, the vaccine is offered in two or three doses over the course of six months to girls who are between 11 and 12, with a catch-up series recommended no later than age 26.
In 2011, the vaccine was also recommended for boys of the same age.
But both health experts and the general public have wondered if expanding vaccine coverage has had the desire effect yet.
For the study, published in the Journal of the American Medical Association, the team looked at data on oral HPV infections in the US between 2009-2016.
From the National Health and Nutrition Examination Survey, they examined rates in unvaccinated men and women from ages 18 to 59.
Researchers found that oral HPV infections fell from 2.7 percent to 1.6 percent – about a 40 percent drop – in unvaccinated men.
However, there was no significant change in prevalence among unvaccinated women.
The team says its findings suggest there is ‘herd immunity’ among men, meaning enough people were vaccinated against the disease so that they were immune to it and unable to spread it.
But they attribute this to rising HPV vaccination rates in women.
According to the most recent data from the Centers for Disease Control and Prevention (CDC), about 50 percent of girls between ages 13 and 17 and 37.5 percent of boys in the same age range were up-to-date on the HPV immunization schedule in 2016.
When the Gardisil vaccine was introduced to the market in 2006, many medical professionals administering the first dose declared it could only be given to virgins because they were the least likely to be exposed to HPV strains.
The thinking was that if a teenager had already had sex, they’d already likely been exposed to a virus strain.
However, several studies have since shown that the virus can be contracted even if one is not sexually active.
There are two ways this can occur. The first is through other forms of genital contact such as hand-to-genital or mouth-to-genital.
Because HPV is transmitted through skin-to-skin contact, it can also be picked up from touching an unsanitized surface such as a table at a doctor’s office or at a gym.
In 2017, new guidelines from the Advisory Committee on Immunization Practices declared the vaccine would be administered in two doses over six months instead of three doses.
The new rules came after years of campaigns from cancer experts insisting an easier schedule would encourage more people to protect themselves from the sexually-transmitted infection.
Despite strong evidence of safety and effectiveness, vaccination rates in the US remains very low compared to other countries, including Spain, Portugal, Greece, Australia and New Zealand.
Each year about 19,000 cancers caused by HPV occur in women in the US, with cervical cancer being the most common, the CDC states.
And about 8,000 cancers caused by HPV occur each year in men in the US and oropharyngeal (throat) cancers are the most common