A new research, funded by Cancer Research UK, has found that the human papillomavirus (HPV) vaccine, which protects against cervical cancer in women, reduced the risk of developing the cancer by 62 per cent in women between the ages of 14 and 16.
It reduced the risk by 34 per cent in women who were aged 16-18 years when they were offered the jab. The paper was published in the journal Lancet this week and looked at all cervical cancers diagnosed in England in women aged between 20 and 64 years, between January 2006 and June 2019.
The results are important because the vaccine was introduced in the 2000s and studies confirming that it is effective against cancer have come up only recently.
Essentially, the study shows that the HPV vaccination in combination with cervical cancer screening reduces the cancer to a point where almost no one develops it. It also shows that over a period of 11 years (since 2006), the vaccine prevented around 450 cervical cancers and around 17,200 cases of precancerous conditions. England extended administration of the vaccine to boys aged 12-13 years in 2018.
What is HPV?
HPV is a type of virus, of which there are more than 100 types. The National Cancer Institute (NCI) notes that more than 40 types of HPV are spread through direct sexual contact. Out of these 40, two cause genital warts, while about a dozen of HPV cause different types of cancer including cervical, anal, oropharyngeal, penile, vulvar and vaginal.
Significantly, almost all cervical cancers are caused by HPV and the vaccine protects against two of the cancer-causing strains, which are HPV 16 and 18.
Once infected, most people do not develop any symptoms, thereby are not aware that they have the virus. In most cases, the body’s immune system will be able to clear the virus out, which means it won’t do any harm to the individual. Even so, the virus can sometimes take years before it causes any symptoms.
How many types of HPV vaccines are there and who should get it?
There are various types of HPV vaccines, including the quadrivalent vaccine (Gardasil), which protects against four types of HPV (HPV 16, 18, 6 and 11). The latter two strains cause genital warts. The other kind of vaccine is the bivalent vaccine (Cervarix), which protects against HPV 16 and 18 only. The third type is a non valent vaccine (Gardasil 9), which protects against nine strains of HPV.
These vaccines prevent cervical cancer in women and girls who have not yet been exposed to the virus. The US Centers for Disease Control and Prevention (CDC) recommends that the vaccine be given to girls and boys between the ages of 11 and 12.
Ideally, the vaccine should be administered before the individual makes their first sexual contact. While for teenagers, the vaccine is administered in a two-dose regimen, for those between the ages 15-26, a three-dose regimen is used in the US.
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HPV vaccination and cervical cancer incidence in India
In India, bivalent and quadrivalent HPV vaccines were licensed in 2008 and a non valent vaccine was licensed in 2018. The Indian Academy of Pediatrics Committee on Immunization (IAPCOI) recommends that HPV vaccines be given as a two-dose regimen, six months apart for girls below the age of 14 years. For those who are 15 and older, the vaccine is given in a three-dose regimen.
A paper published in the Asian Pacific Journal of Cancer Prevention notes that in India, the primary obstacle to HPV vaccination is financial. It also says that while India is home to 16-17 per cent of the world’s population, globally 27 per cent of total cervical cancer cases are from here. Further, in India about 77 percent cases of cervical cancer are caused by HPV 16 and 18.
There is no recommendation for HPV vaccines for boys and males in India yet.
