By Nick Triggle
Health reporter, BBC News
People with chlamydia may not have any symptoms
The chlamydia screening programme in England reached just a third of the people it should have in its first full year, the BBC has learned.
Ministers set local health bosses a target of screening 15% of the 15-24 age group, but fewer than 5% were.
The shortfall has been blamed on delays getting programmes started and problems engaging young people.
Chlamydia is the most common sexual infection, with young people accounting for two thirds of all new diagnoses.
It is known as the "silent infection", as it often shows no symptoms, but if left untreated can cause infertility.
Last year there were more than 79,557 cases among the under 25s, meaning the rate has more than doubled in the last nine years.
The screening programme was introduced in several pilot areas in 2002 to address the risks from the rising number of cases.
Screening is done via urine tests, mainly in contraceptive clinics, GP surgeries or through outreach work in bars, clubs and colleges, as it has been designed to get to people not using sexual health services.
Over the last few years, testing has been gradually rolled out across the country, with the government pumping £70m into the NHS to get it fully up and running by 2007-8.
However, just over 319,000 tests were done - 4.9% of the 15 to 24-year-old population. About one in 10 was positive.
Only three of England's 152 PCTs hit the required 15%, with Barnsley testing just 125 people - 0.5% of the age group.
The BBC was told by officials involved in the project that poor coordination by primary care trusts and budget pressures meant some of the programmes did not get started until half-way through the year.
Dr Tim Crayford, president of the Association of Directors of Public Health, which represents the PCT officials overseeing the programme, said the uptake was "disappointing".
"It is certainly a hard to reach age group and we needed more evidence on how to get them to agree to testing.
"Many screening initiatives, such as breast cancer, rely on 'call and re-call', whereby letters are sent out to women, but this has not really been done for this programme."
Paul Ward, deputy chief executive of the Terrence Higgins Trust sexual health charity, which runs some of the outreach testing, said the programme should have done better.
But he added: "The important thing now is to build on this and make sure we reach more young people from now on."
Simon Blake, chief executive of Brook, the sexual health charity for young people, said: "It is clearly not good enough. We have to get better and that means engaging with young people."
A Department of Health spokeswoman admitted trusts were finding it "challenging".
She said the sexual health national support team, a government-appointed group of experts, was now working to help areas improve.
Neither Scotland, Wales or Northern Ireland has set up a chlamydia screening programme.