Boys in the UK will be given the HPV jab in a bid to prevent thousands of cases of cancer each year.
From Monday September 1 the vaccination programme, which currently only covers girls, will be given to boys aged 12 to 13.
Experts hope that by rolling out the programme to boys, they can prevent 64,138 cervical and 49,649 non-cervical cancers in the UK by 2058.
The jab protects against the human papillomavirus, a viral infection that can lead to cervical, penile, anal and genital cancers, along with cancers of the neck.
Here is all you need to know about the HPV virus and its vaccine.
What is the HPV virus?
The human papillomavirus (HPV) is a sexually transmitted virus linked to more than 99% of cervical cancers, as well as 90% of anal cancers, about 70% of vaginal and vulvar cancers and more than 60% of penile cancers.
The virus, of which there are more than 100 varieties, is passed through intimate skin-to-skin contact and can affect the genitals, mouth or throat.
According to the NHS, it is extremely common and most people will get some type of the virus in their life. HPV has no symptoms and most of the time does not cause problems, but can cause genital warts and cancer.
There is no treatment for infection, but most are cleared by your body within two years.
How can HPV cause cervical cancer?
Changes in the cervix are almost always caused by the human papilloma virus (HPV).
The NHS says there are more than 100 types of HPV and around 30 types affect the genital area.
Some will cause abnormal changes in cells which can sometimes turn into cancer.
Most cervical cancers are caused by high-risk types HPV-16 and HPV-18.
What is the HPV vaccine?
The HPV vaccination programme was introduced to Britain around 50 years ago and girls in Year 8 have been offered the vaccine free in school since 2008.
PHE said the programme meant infections of some strains of HPV in youngsters aged 16 to 21 have fallen by 86% in England.
A Scottish study also suggested the vaccine had reduced pre-cancerous cervical disease in women by up to 71%.
Similarly, diagnoses of genital warts have declined by 90% in 15 to 17-year-old girls and by 70% in 15 to 17-year-old boys.
From the start of the next school year, boys in Year 8 who are aged 12 and 13 will be given the jab with parental consent.
The first dose will be given in school in Year 8, with a follow-up dose six months to two years later, also given in school.
The HPV jab currently used by the NHS is Gardasil, which protects against HPV for at least 10 years and possibly a lifetime.
Giving boys the jab also protects girls from HPV.
PHE said there will be no catch-up programme for older boys aged 13 to 18.
Why do children get the vaccine at such a young age?
Since the virus is spread during sexual activity or skin-to-skin contact, it is best to vaccinate people before they become sexually active.
According to the NHS, the jab will work best before children have a chance to come into contact with the virus.
So it is hoped the vaccine will protect them for years afterwards.
Are there any side effects?
The NHS says that common side effects include
- bruising or itching at the site of the injection
- redness, swelling or pain at the side of injection
- a high temperature or feeling hot and shivery
- pain in the arms, hands, fingers, legs, feet or toes
Uncommon side effects include hives, difficulty breathing and feeling dizzy or faint afterwards.