A jab that protects against a virus that causes cervical cancer should also be given to boys, an advisory committee has recommended.
The HPV vaccine is routinely offered to girls aged 12 to 13 at secondary school and is free up until they turn 18.
Now the Joint Committee on Vaccination and Immunisation has advised extending immunisation to adolescent boys at the same age as girls.
The government said it would carefully consider the advice.
Other health bodies welcomed the committee's recommendation, adding that boys had been insufficiently protected against HPV "for too long".
HPV is the name given to a large group of viruses.
It is very common and can be caught through any kind of sexual contact with another person who already has it.
Doctors say most HPV infections go away by themselves – but sometimes infections can lead to a variety of serious problems.
For boys, this includes cancer of the anus, penis, mouth and throat.
The vaccine has been offered to girls since 2008 as part of the NHS childhood vaccination programme.
But campaigners have long since argued that it should also be offered to boys to further reduce the risk of HPV infection, pointing to successful vaccination programmes in other countries.
In July last year, the JCVI was criticised after it said in an interim statement that it could not recommend extension of the national HPV programme.
However, a report by the committee, published on Wednesday, said: "If considering a cost-effectiveness analysis where a combined girls' and boys' programme is compared to no vaccination, gender-neutral HPV vaccination is highly likely to be cost-effective."
The Royal Society for Public Health said the decision was "a victory for the public's health".
Chief executive, Shirley Cramer, said: "Boys have been left insufficiently protected against HPV for too long and it is good news that the UK is following in the footsteps of the other 20 countries already vaccinating boys against HPV."
The campaign group HPV Action welcomed the JCVI's statement this year and called for the Department of Health and Social Care to accept its findings.
A Department of Health and Social Care spokeswoman said it would provide an update on its decision shortly.