A multi-million pound chlamydia screening programme isn't getting to enough young people. The idea was to get 15% of 15 to 24-year-olds in England tested, but the reality is more like 5%. Officials think things are getting better, but critics say it's just not good enough.
By Catherine Burns
Newsbeat health reporter
An examining room at the Central Middlesex Hospital
There are plenty of nervous faces in the waiting room for the GUM (Genitourinary medicine) clinic at the Central Middlesex Hospital.
You get given a number so they don't have to call your name out loud when it's your turn.
Most people don't want to talk about why they've come, but one girl chats happily away.
A few months ago, she got a new boyfriend, so they both decided to get checked out for STIs. It turned out she had chlamydia.
She says she was devastated and embarrassed when she found out.
She said: "You just don't think you're going to have it, you just feel disturbed by it."
That was three months ago. She was given a course of tablets and is fine now.
She's back today for another check-up, just to double check she's OK.
The staff are more than happy to put her mind at rest.
A nurse takes her into an examining room and talks her through the test.
They'll give her a pot to pee in, and in two weeks, the results will be back.
But the Government is worried not enough people are coming to clinics.
Chlamydia is the most common STI. The good news is that it's easily treated.
But hardly anyone gets symptoms, so people often don't realise they've got it.
Dr Gary Brook is the head of sexual health.
Dr Gary Brook works at Central Middlesex Hospital
He said: "It causes major, major problems. It's like a time bomb, that if it's not dealt with is going to lead to infertility later on in life."
Over the last few years, the government has started a £70m screening programme across England.
The idea is to reach young people who wouldn't normally go to places like an STI clinic.
So as well as GP surgeries, health workers target bars, festivals and clubs.
James was tested in his gym. He wasn't going to bother, but it was easy to get it done then and there.
He said: "When you're young, you think you're invincible, and I thought I'd be all clear, I thought I'd be OK.
"So when I had it, I was really shocked actually. But when it was explained how easily it could be cleared and how common it was, I was reassured."
James is a success story for the screening programme.
But the problem is, nowhere near enough people are getting tested through it.
There are a two main reasons for that.
For a start, it's been difficult persuading busy GPs to add to their workload.
But also, experts say it's difficult to persuade young people to realise the risks and get themselves checked out.
Sexual health charities are less than impressed with this.
Simon Blake is from Brook. He said: "It is clearly not good enough. We have to get better, and that means engaging with more young people."
But people here say things are getting better.
Dr Brook says more and more people are coming forward for tests.
He added: "The numbers are doubling every six months or so. I think we will find the 15% target is reached in the not-too-distant future."
James says now he's been tested, he's not going to take any more risks.
He said: "You speak to the girl before and they're like, 'Oh I'm clean,' so you think, 'Give it a go.'
"And it has taught me to be a bit more cautious. That's for sure."