SARS-CoV-2 Saliva Testing to Determine Viral Shedding Duration in Hemodialysis Patients

ABSTRACT

Background: Hemodialysis (HD) patients are vulnerable to COVID-19. Early detection of COVID-19 in dialysis clinics informs isolation and infection control policies. Saliva testing is an alternative to nasopharyngeal swab to detect SARS-CoV-2. The understanding of viral shedding in HD patients is limited. We explore viral shedding duration in HD patients and determine its correlation with immunosuppression. Method(s) Eligible patients diagnosed with COVID-19, confirmed by nasal swab RTPCR within 2 weeks of COVID-19 diagnosis, were recruited. They were given Salivette Saliva Collection kits and instructed to chew a cotton swab for 60 seconds. Result(s) 30 COVID-19 positive patients participated (Table 1). Each patient provided up to 7 saliva samples. 65 samples were collected for an average of 11+/-8 days (range 0-36) after diagnosis. 26 samples showed at least one COVID-19 target gene (N, ORF1ab) with cycle threshold <38 cycles. 12 patients had at least 1 positive sample, and 23 patients had at least 1 negative sample. Of the 23 patients who had at least one negative sample, median days to first negative sample is 9 days (range 0-36). For the 7 patients who only had positive samples, median days to last positive sample is 9 days (range 0-36). There is no observed difference between vaccinated (n=24) and vaccinated patients (n=6). 6 out of 30 patients took immunosuppressants such as Tacrolimus, Hydroxychloroquine, and Mycophenolate sodium. Median days to turn negative (or use last positive date if negative results never achieved) was 15 days for immunocompromised group and 8 days for nonimmunocompromised group (Fig.1) Conclusion(s) Immunocompromised HD patients shed COVID-19 virus for a significantly longer period. While our study did not explore the shedding of viable SARS-CoV-2, a longer isolation should be considered in immunosuppressed HD patients. Studies on shedding of viable SARS-CoV-2 are warranted in immunocompromised HD patients to inform policies regarding isolation and contact tracing protocols, and vaccination strategies.