HPV vaccine leads to steep drop in cancer-causing infections in England
Posted June 15, 2018 4:32 a.m. EDT
(CNN) — The introduction of HPV vaccines has led to a sharp reduction in the number of young women with the cancer-causing infection in England, new data from Public Health England finds.
Between 2010 and 2016, infections with HPV 16 and 18 fell 86% among women ages 16 to 21 who were eligible for the vaccine during this time period. HPV 16 and 18 are two types of human papillomavirus responsible for most cervical cancer cases.
Overall, the HPV vaccination program, first introduced in 2008, led to a decline in five types of high-risk HPV, which cause almost 90% of cervical cancer cases, according to the study published Monday in the Journal of Infectious Diseases.
The incidence of less risky strains of HPV also decreased.
"The study shows the positive effects of HPV vaccinations," said David Mesher, principal STI prevention scientist at PHE, and lead author of the study. "There have been some very positive results from the program."
The study also found a decline in various kinds of HPV that are not protected against by the vaccine, lending evidence to the idea that the vaccine can prevent other strains of the virus.
"There are lots of different HPV types and some types are closely related. Similar types tend to have some cross-protection," said Mesher.
The new findings add to the growing body of evidence for the vaccine's effectiveness.
The study sampled 15,349 women aged 16 to 24 who came in for chlamydia screening across England between 2010 and 2016.
As well as HPV infections, there was also a decline in the number of genital warts diagnoses among both girls and boys aged 15 to 17 between 2009 and 2017.
Genital warts are caused by certain strains of HPV that the vaccine protects against, according to John Doorbar, professor of viral pathogenesis at Cambridge University, who was not involved in the study.
HPV spreads through sexual contact with someone who is already infected. According to the US Centers for Disease Control and Prevention, "almost every person who is sexually-active will get HPV at some time in their life if they don't get the HPV vaccine."
In women, persistent HPV infections can eventually develop into cervical cancer -- the fourth most frequent cancer in women globally.
The vaccine is typically given to girls at age 12 or 13, as it works more effectively then, according to Masher.
It's a simple vaccine, just a mimic of the virus particle, that when administered into your muscle creates many more antibodies than you'd get during a natural infection, Doorbar explained.
"The HPV vaccine works better than anybody would have expected," he added.
There are over 100 types of HPV. However, the vaccine doesn't protect against all of these strains.
"This is the main limitation of current vaccines. They are unable to protect against all HPV types. However, some types are more important for cancers than others and the key ones that cause cancers, the vaccine has protected against," said Doorbar.
In the UK, over 80% of women between the ages of 15 and 24 have been vaccinated against HPV. Globally, 80 million people, both men and women, have been vaccinated, according to the PHE.
Dr. Vanessa Saliba, consultant epidemiologist at PHE, said more and more countries are establishing programs and pushing to improve access.
Global HPV vaccination coverage has increased over the last 10 years, but even in some of the world's more affluent countries, such as the Unites States, France, Denmark and Japan, vaccination levels are low.
There is ongoing debate in the UK about giving the vaccine to boys because HPV has been linked to other types of cancers, such as anal, penile and throat cancer. But some experts argue that giving the vaccine solely to women is more cost-effective and that they are disproportionately affected by the infection.
"It's really important that we get this message out about what a difference the vaccine is making so that we maintain our high uptake rates going forward and make sure that all our girls are protected as early as possible," said Saliba.