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Background Most diagnostic tests for SARS-CoV-2, the causative agent of COVID-19, are RT-PCR based. This method is sensitive but cannot distinguish replicating from non-replicating virus. RT-PCR cycle threshold (Ct) values are inversely correlated with viral load, and higher Ct values have been correlated with lower in vitro viral infectivity. However, relatively few data exist on the association between Ct values and patients’ duration of symptoms remains unclear. We thus evaluated Ct values and symptom duration in a cohort of patients hospitalized with COVID-19. Methods We assessed all patients admitted to San Francisco General Hospital between April 1 and May 18, 2020 with confirmed COVID-19 infection based on RT-PCR testing (Abbott m2000 platform). We included patients having diagnostic testing for suspected COVID-19 and patients having asymptomatic testing per hospital policy. For symptomatic patients, date of symptom onset was abstracted from hospital records, and time from symptom onset to test date was calculated. RT-PCR Ct values were manually extracted. Median Ct and IQR were calculated for patients with < 10 days of symptoms, ≥10 days of symptoms, and asymptomatic disease. Between-group comparisons were performed using the Kruskal-Wallis test. Results Among 61 patients with positive RT-PCR tests, 40 patients reported < 10 days of symptoms at the time of testing, 15 reported ≥10 days of symptoms, and 6 were asymptomatic. The median Ct value was 14.2 cycles (IQR, 10.2, 18.3) among patients reporting < 10 days of symptoms, 19.7 cycles (IQR, 15.3, 23.9) among patients reporting ≥10 days of symptoms, and 26.3 (IQR, 25.0, 29.1) among asymptomatic patients. Ct values were significantly lower among patients with < 10 days of symptoms compared to patients with >=10 days of symptoms (p=0.01) and when compared to asymptomatic patients (p=0.0002) [Figure]. Cycle threshold (Ct) by days of symptoms at time of testing Conclusion SARS-CoV-2 RT-PCR cycle threshold values were higher (indicating lower viral load) in patients with longer symptom duration and were highest in asymptomatic patients. These results add to emerging data suggesting that strategies for optimal isolation of patients in both community and hospital settings could be informed by a combination of symptom duration and RT-PCR Ct values. Disclosures All Authors: No reported disclosures

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Student absenteeism affects students’ engagement in school and academic and professional success. While research documents a significant association between school bullying/fighting and student absenteeism due to fear of being at school or getting to school, little research has examined the association of adolescent dating violence (ADV) victimization with this type of absenteeism. This study examined the relationship between physical and/or sexual ADV victimization in the past year (dichotomized as yes or no), and number of days of student absenteeism due to feeling unsafe at school or on the way to school in the past month (dichotomized as any vs. none). We analyzed cross-sectional data from the 2019 Youth Risk Behavior Survey (YRBS), a nationally representative survey of U.S. high school students ( n = 9507). We conducted crude and multivariate regression models for the total sample and stratified by sex to assess our hypothesized association of ADV victimization and absenteeism; sex, grade, race/ethnicity, and sexual identity were included as covariates in adjusted models. Findings demonstrate that students reporting past year ADV victimization had 3.69 times the odds of student absenteeism due to feeling unsafe, when compared to students who did not report ADV victimization (95% CI: 3.06–4.45, p < 0.001). Sex-stratified models reveal that this effect is significantly stronger for males than for females, as indicated by non-overlapping confidence intervals (male AOR: 5.67, 95% CI: 4.18–7.68; female AOR: 2.95, 95% CI: 2.32–3.74). The multivariate models also show that Black and Latinx compared with White students, and lesbian/gay/bisexual/unsure compared with heterosexual students, had higher odds of student absenteeism due to feeling unsafe. Findings indicate the need to address ADV victimization and student absenteeism with integrated and gender-tailored responses, and with consideration of greater vulnerabilities for queer students and students of color.