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Original article
Is chlamydia screening and testing in Britain reaching young adults at risk of infection? Findings from the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3)
  1. Sarah C Woodhall1,2,
  2. Kate Soldan2,
  3. Pam Sonnenberg1,
  4. Catherine H Mercer1,
  5. Soazig Clifton1,3,
  6. Pamela Saunders4,
  7. Filomeno da Silva4,
  8. Sarah Alexander4,
  9. Kaye Wellings5,
  10. Clare Tanton1,
  11. Nigel Field1,
  12. Andrew J Copas1,
  13. Catherine A Ison4,
  14. Anne M Johnson1
  1. 1Research Department of Infection and Population Health, University College London, London, UK
  2. 2Centre for Infectious Disease Surveillance & Control (CIDSC), Public Health England, London, UK
  3. 3NatCen Social Research, London, UK
  4. 4Microbiology Services, Public Health England, London, UK
  5. 5Department of Social and Environmental Health Research, London School of Hygiene and Tropical Medicine, London, UK
  1. Correspondence to Sarah C Woodhall, HIV & STI Department, Public Health England, 61 Colindale Avenue, London NW9 5EQ, UK; sarah.woodhall{at}


Background In the context of widespread opportunistic chlamydia screening among young adults, we aimed to quantify chlamydia testing and diagnosis among 16–24 year olds in Britain in relation to risk factors for prevalent chlamydia infection.

Methods Using data from sexually experienced (≥1 lifetime sexual partner) 16-year-old to 24-year-old participants in Britain's third National Survey of Sexual Attitudes and Lifestyles (conducted 2010–2012), we explored socio-demographic and behavioural factors associated with prevalent chlamydia infection (detected in urine; n=1832), self-reported testing and self-reported diagnosis in the last year (both n=3115).

Results Chlamydia prevalence was 3.1% (95% CI 2.2% to 4.3%) in women and 2.3% (1.5% to 3.4%) in men. A total of 12.3% of women and 5.3% men had a previous chlamydia diagnosis. Factors associated with prevalent infection were also associated with testing and diagnosis (eg, increasing numbers of sexual partners), with some exceptions. For example, chlamydia prevalence was higher in women living in more deprived areas, whereas testing was not. In men, prevalence was higher in 20–24 than 16–19 year olds but testing was lower. Thirty per cent of women and 53.7% of men with ≥2 new sexual partners in the last year had not recently tested.

Conclusions In 2010–2012 in Britain, the proportion of young adults reporting chlamydia testing was generally higher in those reporting factors associated with chlamydia. However, many of those with risk factors had not been recently tested, leaving potential for undiagnosed infections. Greater screening and prevention efforts among individuals in deprived areas and those reporting risk factors for chlamydia may reduce undiagnosed prevalence and transmission.


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