2.6. Collection of nasopharyngeal swab and saliva samples

Nasopharyngeal swab (NPS) and saliva samples were collected from asymptomatic and symptomatic COVID-19 patients under institutional review board (IRB) approval (UCSD protocol #200477). NPS samples were collected in either DNA/RNA Shield storage medium (Zymo) or viral transport medium, which was prepared according to CDC guidelines [11]. Healthy volunteers also provided 300–500 µL saliva in sterile tubes using a passive drooling method [12]. Saliva samples contained no additives, and all clinical samples were stored in 300 µL aliquots at -80 °C. All samples were confirmed positive under clinical conditions via RT-qPCR tests: briefly, viral RNA was extracted from samples using the MagMax Viral/Pathogen Nucleic Acid Isolation Kit (Thermo), and RNA was amplified/quantified using the TaqPath COVID-19 multiplex RT-qPCR assay (Thermo). Saliva samples were blinded and tested in a Biosafety Level 3 (BSL-3) laboratory, and all experimentation followed UCSD Human Research Protections Program (HRPP) guidelines and regulations. Table 4 lists relevant demographic information for this cohort.