The Government will officially roll out its campaign today to vaccinate young girls against a virus that causes cervical cancer.

Social networking sites have already been targeted in a bid to encourage girls to have the jab which helps protect against human Papillomavirus (HPV).

HPV is a sexually-transmitted infection that causes most cases of cervical cancer.

Schools across the UK will start vaccinating pupils aged 12 and 13 (Year 8) from this week onwards with around 300,000 girls receiving the jab in England alone.

By July 2011, more than two million girls will have been offered the vaccine, including those up to the age of 18 as part of a catch-up programme.

The Government's campaign for England, which is launched today, includes online, press, TV and radio advertising.

A series of roadshows will also be held in shopping centres across the country.

Earlier this week the Government targeted social networking websites Habbo Hotel and Lola's Land, which are now are featuring adverts for the vaccine.

Adverts and text on the Lola's Land website for young girls says: "Remember chica, this is a totally life-saving, revolutionary vaccine!

"Let's fight cervical cancer together and arm ourselves against it!"

The text of the advert reads: "If you're in Year 8, arm yourself against cervical cancer."

Adverts and Q&A-style features have also been put on the Habbo Hotel "virtual world" website.

The Government's main campaign will run this month and next, with some follow-up advertising in February to remind girls not to miss their third and final injection.

Girls aged 17 and 18, who form part of the catch-up programme, will be the target of a different advertising campaign in October.

Primary care trusts (PCTs) are responsible for administering the jab - which is not compulsory - in England.

Details of how many girls receive the jab will be collected locally by PCTs and then fed centrally for analysis either by the Department of Health or the Health Protection Agency (HPA).

News of the campaign comes after a former school nurse expressed her belief that there might not be enough school nurses to deliver the jabs.

Kate Forbes, who now works in a sexual health clinic, wrote in the British Journal of School Nursing that local health trusts faced a "tough challenge" to implement the programme against a backdrop of cost-cutting and a "destabilised" workforce.

And last week, a health expert called for young boys to also be vaccinated to stop them passing the infection on to girls.

A spokesman for the Department of Health said: "It does not have to be a school nurse that administers the vaccinations. Anyone who is a registered nurse can do this.

"Many PCTs are gathering their nurses into teams including health visitors, registered paediatric nurses, practice nurses and managers who have retained their nursing expertise.

"DH (the De8partment of Health) will be providing about £18.9m in total to PCTs in the 2008/09 financial year to support the vaccination of girls in school years 8 and 13.

"The funding for PCTs will pay for providers to give the vaccine and other local operational costs."

The HPV vaccine protects against over 70 per cent of the strains that cause cervical cancer, which accounts for around 1,000 deaths a year in the UK.

The Department of Health announced in June that pharmaceutical giant GlaxoSmithKline had won the contract to provide the Cervarix jab.

The move led to an outcry from some campaigners, who said the decision was based on cost and that the Government should have opted for the vaccine Gardasil, from Merck, which also protects against genital warts.

Lisa Power, head of policy at the Terrence Higgins Trust, accused the Government of "saving pennies to spend pounds later" by not choosing Gardasil.

Smear testing will continue even after the vaccine is introduced.

This is because of the gap between the age of vaccination and the age of first screening, and because the jab does not protect against all HPV types that may cause the disease.

As well as those diagnosed with cancer, around 200,000 women a year in the UK have pre-cancerous changes to their cervix picked up through smear tests.