Background CT remains the most prevalent sexually transmitted infection in developed and developing countries. Prevention of infection is an ideal application for a vaccine program. Similar to the HPV vaccine, the timing of immunisation for a future CT vaccine should optimally precede sexual debut. However, there are limited epidemiologic studies of CT infection in an unselected paediatric and adolescent population since universal screening and treatment of pregnant women was implemented in the US in 1993.

 Objective To determine current seroepidemiology of CT infection in children in a US inner city population.

Design/methods Anonymized serum samples were obtained from children in 2 hospitals in Brooklyn, NY from 2012–2015. CT IgG was determined using EIA (Ani Labsystems). The following age strata were used: 11–12, 13–14, 15–16, 17–18, 19–20 y.

Results 512 sera were included in the final analysis. Mean age 17 y. There were 192 (37.5%) males and 320 (62.5%) females. CT antibody was first detected at 16 y and 18 y for females and males, respectively. The prevalence per age-cohort were: Females: 11–14 y-0, 15–16 y- 3.64%, 17–18 y -15.9%, 19–20 y -14.75%; Males: 11–16 y- 0, 17–18 y- 8.51%, 18–20 y- 9.33%.

Conclusions The prevalence of antibody was higher in girls than their male counterparts, mirroring national trends based on NAATs. Antibody was first detected in females at 16 y and males at 17 y, reflecting sexual debut. Prior data from this cohort found antibody in% infants < 1 y, which disappeared between 1 and 16 y. The delay in male antibody detection may be due to later exposure and/or anatomical and physiological factors between the sexes. These data are critical in informing potential CT vaccine strategies. Future studies using a larger sample size and other populations will allow more precise estimates of age and gender-specific prevalence.