1 SCIENTIFIC REPORTS | (2019) 9:14479 | https://doi.org/10.1038/s41598-019-51128-6 www.nature.com/scientificreports Universal HIV and Birth Cohort HCV Screening in San Diego Emergency Departments Martin Hoenigl 1 , Kushagra Mathur 2 , Jill Blumenthal 1 , Jesse Brennan 3 , Miriam Zuazo 1 , Melanie McCauley 1 , Lucy E. Horton 1 , Gabriel A. Wagner 1 , Sharon L. Reed 4 , Gary M. Vilke 3 , Christopher J. Coyne 3 & Susan J. Little 1 Universal HIV and HCV screening in emergency departments (ED) can reach populations who are less likely to get tested otherwise. The objective of this analysis was to evaluate universal opt-out HIV and HCV screening in two EDs in San Diego. HIV screening for persons aged 13–64 years (excluding persons known to be HIV+ or reporting HIV testing within last 12 months) was implemented using a 4 th generation HIV antigen/antibody assay; HCV screening was ofered to persons born between 1945 and 1965. Over a period of 16 months, 12,575 individuals were tested for HIV, resulting in 33 (0.26%) new HIV diagnoses, of whom 30 (90%) were successfully linked to care. Universal screening also identifed 74 out-of-care for >12-months HIV+ individuals of whom 50 (68%) were successfully relinked to care. Over a one-month period, HCV antibody tests were conducted in 905 individuals with a seropositivity rate of 9.9% (90/905); 61 seropositives who were newly identifed or never treated for HCV had HCV RNA testing, of which 31 (51%) resulted positive (3.4% of all participants, including 18 newly identifed RNA positives representing 2% of all participants), and 13/31 individuals (42%) were linked to care. The rate of newly diagnosed HCV infections exceeded the rate of newly diagnosed HIV infections by >7-fold, underlining the importance of HCV screening in EDs. Nearly 40,000 individuals in the United States were newly diagnosed with HIV in 2017 1 . Additionally, at the end of 2015, about 165,000 individuals in the United States were unaware of their HIV positive status, with particu- larly high rates observed among younger Latino or Black men with heterosexual risk 1 . Tose currently unaware of their HIV infection are not only at risk of sufering personal health consequences but may also unknowingly transmit HIV to others. About 40% of new HIV infections are transmitted by individuals living with undiagnosed HIV 1 . As a result, the Centers of Disease Control and Prevention (CDC) currently recommends routine universal HIV screening for all persons 13–64 years of age 2 . Although targeted testing of those engaged in transmission risk behaviors, such as sexually active men who have sex with men (MSM) and people who inject drugs results in a higher yield of HIV diagnoses 3–6 , universal (i.e. opt-out) HIV screening in emergency department (ED) settings has the potential to reach populations who do not consider themselves at risk or are otherwise less likely to seek out and participate in HIV testing 7,8 . Another important aspect of universal HIV testing programs in the ED is fnding known HIV+ individuals infected who have fallen out of care. Te ED setting has been demonstrated to be efective not only for HIV screening, but also for screening for hepatitis C virus (HCV) infection 9 . While the number of deaths associated with HCV had been increasing dramatically until 2013 10 , the introduction of direct-acting antiviral therapy has since turned HCV infection into a curable disease 11,12 . In response, a growing number of EDs are screening for HCV infection, particularly among baby boomers born between 1945 and 1965 13 . Te CDC recommends routine HCV screening for this birth cohort, due to the high frequency of illicit drug use and contaminated transfusions that occurred in the 1970s and 80s 14 . 1 Department of Medicine, Division of Infectious Diseases and Global Public Health, University of California San Diego, San Diego, California, United States. 2 University of San Diego School of Medicine, San Diego, California, United States. 3 Department of Emergency Medicine, University of California San Diego, San Diego, California, United States. 4 Department of Pathology, University of California San Diego, San Diego, California, United States. Martin Hoenigl and Kushagra Mathur contributed equally. Christopher J. Coyne and Susan J. Little jointly supervised this work. Correspondence and requests for materials should be addressed to M.H. (email: mhoenigl@ucsd.edu) Received: 21 February 2019 Accepted: 25 September 2019 Published: xx xx xxxx OPEN