Chlamydia trachomatis (chlamydia) is a common bacterial sexually-transmitted infection. In England, sexually-active 15-24 year olds are opportunistically screened for the presence of chlamydia infection via the National Chlamydia Screening Programme (NCSP). Individuals testing positive for chlamydia are given appropriate treatment according to NCSP guidelines.

Recently, these guidelines were updated to recommend re-testing for chlamydia three months after treatment. However, no guidance has been given to local areas on the most economical way of delivering retesting. Specifically, we do not know the best way to balance getting the optimal number of people to re-test versus the additional cost of delivering invitations or reminders to retest.

Scientist viewing specimen through a microscope in a laboratory.

Project aim

To compare the relative cost of different methods of delivering chlamydia re-testing, taking into account the proportion of people who re-test for each of these different methods.

Anticipated impacts

This work will help guide the best way to deliver chlamydia re-testing at the local level across England. This work has resulted in submission of a short report to a peer review journal which will provide evidence for UK Health Security Agency guidance. The work will also be of interest to other countries which offer chlamydia screening.


National Institute for Health and Care Research (NIHR).

Project dates

Jan 2016 – April 2018

Lead researcher

Katy Turner, Dr (University of Bristol)