HPV can cause cancers in both genders – so should boys be vaccinated too?
Experts explain how the vaccine works, and the Ministry Of Health sheds light on why the National Childhood Immunisation Schedule only covers girls.
If you’re a parent of a teenager, you might be attuned to the Ministry Of Health’s opt-in human papillomavirus (HPV) vaccination offered under the National Childhood Immunisation Schedule for Secondary 1 female students starting this April.
WHAT IS HPV?
Cervical cancer is the fifth-most common cancer among women in Singapore and is caused by HPV.
HPV is a group of more than 200 related viruses, of which more than 40 are spread through direct sexual contact, noted the US National Cancer Institute (NCI).
To date, there are around 14 HPV viruses that have been linked to the development of cancer, according to Dr Ida Ismail-Pratt, Consultant at the National University Hospital’s Division Of Gynaecologic Oncology, Department of Obstetrics and Gynaecology.
The problem with HPV is, the infected individual doesn’t show any symptoms.
And eight out of 10 people will get an HPV infection at some point in their lifetime without knowing it, according to the Singapore Cancer Society.
In most cases, HPV goes away on its own. But sometimes, the infections don’t and can cause certain cancers and other diseases.
SHOULD BOTH GENDERS BE INVOLVED?
HPV 16 and HPV 18 are the most common causes for cervical cancer worldwide, accounting for 70 per cent of cervical cancer cases, said Dr Ismail-Pratt.
HPV can also cause vaginal and vulva cancers.
But here’s where males should also pay attention: “Persistent HPV infection has been linked to the development of penile, anal and oropharyngeal cancers,” she said.
In fact, HPV 16 is known to increase the risk of anal, penile and oropharyngeal, or throat, cancers in men.
"Currently, there is no effective screening tool or strategy for anal cancer as that for cervical cancer," said Dr Ismail-Pratt.
She added: "HPV vaccination in boys not only benefits them in terms of HPV-related infection diseases, but can also help stop the cross infection of cancer-related HPV infection in girls. This is called herd immunity."
SO, WHY AREN’T BOYS INCLUDED?
While HPV can cause genital warts, and cancers of the throat and anus that affect both genders, the public health objective of the MOH initiative is cervical cancer prevention.
As such, the full subsidy on HPV vaccination is only for female students, according to an MOH spokesperson.
"While HPV vaccination confers protection for the prevention of genital warts, as well as some other cancers (for example, anal cancer), which may be applicable to males, these cancers have low incidence in males in Singapore,” said the spokesperson.
“MOH will continue to monitor evidence and review our policy on HPV vaccination for males as and when new evidence emerges on its clinical and cost effectiveness.”
“The HPV vaccine can be given to both boys and girls,” said Dr Ismail-Pratt.
“In Singapore, the HPV vaccine is licensed to be given to boys between 9 and 26 years old for protection against anal cancer and pre-cancer, including genital warts.”
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What does this mean for parents then? “The decision for boys to proceed with the vaccination is a personal choice,” said Dr Edwin Chng, medical director of Parkway Shenton.
“In general, it is the same dosing for boys as it is for girls.”
Said Dr Ismail-Pratt: "For parents who are contemplating vaccinating their sons, a consultation with their doctor is advised to ensure they understand the full benefit of the HPV vaccination for their boys".
HOW THE VACCINE WORKS
The vaccine comprises an empty protein coat that tricks the body into thinking that it has been exposed to HPV infection, said Dr Ismail-Pratt, who explained that the vaccine does not contain any viral DNA in it.
Translated: You won’t get HPV infection from the vaccine. “The body then responds by increasing the antibody levels to fight this exposure,” she said.
There are three HPV vaccines available in Singapore and they all protect against HPV 16 and HPV 18: Cervarix, Gardasil and Gardasil 9, said Dr Ismail-Pratt.
The difference? The amount of protection each vaccine can provide.
For instance, Gardasil 9 gives the widest protection against seven out of the 14 cancer-causing HPV infections known.
Currently, there is no indication for a need for booster jabs after completing the course, she said.
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The US Centers For Disease Control And Prevention noted that the most common side effects from the injections are pain, redness, or swelling in the arm where the shot was given.
There may also be dizziness, fainting, nausea, and headache.
WHAT’S A GOOD AGE TO VACCINATE?
In Singapore, vaccination for girls begins in Secondary 1 when they are 13 years old, and is completed in Secondary 2 at 14 years old.
"Only two doses are needed if the first dose is started before 15 years of age,” said the MOH spokesperson.
Naturally, the vaccine works best before the individual becomes sexually active and increases his or her chances of coming into contact with the virus.
According to the NCI, the current guidelines recommend that both boys and girls aged 11 or 12 years get two HPV vaccine shots six to 12 months apart.
If the two shots are given less than five months apart, a third shot will be needed.
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If you missed this window, the recommendations for females is between the ages of 13 and 26; for males, between 13 and 21, noted the American Cancer Society.
While the vaccine prevents your child from contracting HPV, it doesn’t detect HPV infections.
For females, it is still important to go for Pap smear tests according to national guidelines to detect abnormal, infected cervical cells that have the potential to become cancer, said Dr Ismail-Pratt.
But that may soon be replaced, she added, by a more sensitive cervical cancer screening tool that only needs to be carried out every five years as the new national cervical cancer screening protocol for women aged 30 and above.