Sexually Transmitted Infections Among US Women and Men: Prevalence and Incidence Estimates, 2018.

BACKGROUND The most recent estimates of the number of prevalent and incident sexually transmitted infections (STIs) in the United States (US) were for 2008. We provide updated estimates for 2018 using new methods. METHODS We estimated the total number of prevalent and incident infections in the US for eight STIs: chlamydia, gonorrhea, trichomoniasis, syphilis, genital herpes, human papillomavirus (HPV), sexually transmitted hepatitis B, and sexually transmitted HIV. Updated per capita prevalence and incidence estimates for each STI were multiplied by the 2018 full resident population estimates to calculate the number of prevalent and incident infections. STI-specific estimates were combined to generate estimates of the total number of prevalent and incident STIs overall, and by gender and age group. Primary estimates are represented by medians and uncertainty intervals are represented by the 25th (Q1) and 75th (Q3) percentiles of the empirical frequency distributions of prevalence and incidence for each STI. RESULTS In 2018, there were an estimated 67.6 (Q1=66.6, Q3=68.7) million prevalent and 26.2 (Q1=24.0, Q3=28.7) million incident STIs in the US. Chlamydia, trichomoniasis, genital herpes, and HPV comprised 97.6% of all prevalent and 93.1% of all incident STIs. Persons aged 15-24 years comprised 18.6% (12.6 million) of all prevalent infections; however, they comprised 45.5% (11.9 million) of all incident infections. CONCLUSIONS The burden of STIs in the US is high. Almost half of incident STIs occurred in persons aged 15-24 years in 2018. Focusing on this population should be considered essential for national STI prevention efforts.