Lessons from a multi-country study into persistent and recrudescent trachoma

This article summarises the key lessons learned from a six-country study that collected data on complementary indicators related to Chlamydia trachomatis infection to better understand persistent and recrudescent trachoma. It highlights the practical challenges associated with adding these complementary indicators to routine trachoma surveys (often called ‘plus’ surveys) and suggests ways to address them. Although more complicated and costly to conduct, ‘plus’ surveys can improve data for programmatic decision-making and may enable some countries to reach elimination targets sooner.