Emerg Microbes Infect

. 2021 Jan 19;1-25.
doi: 10.1080/22221751.2021.1878937. Online ahead of print.
Saliva Viral Load Better Correlates with Clinical and Immunological Profiles in Children with Coronavirus Disease 2019

Gilbert T Chua MBBS, FHKAM(Paed) 1 , Joshua Sc Wong MBBS, FHKAM(Paed) 2 , Kelvin Kw To MD, FRCPath 3 , Polly Pk Ho MBBS, FHKAM(Paed) 1 4 , Ivan Cs Lam MBChB, FHKAM(Paed) 1 2 , Jaime Sr Duque MD, PhD 1 , Wai **** Chan MBChB, FHKAM(Paed) 1 4 , Felix Ys Yau MBChB, FHKAM(Paed) 1 4 , Cyril Cy Yip PhD 3 , Anthony Ck Ng MPhil 3 , Wilfred Hs Wong PhD 1 , Joyce Hy Kwong FHKAM(Path) 5 , Kate Fs Leung FHKAM(Path) 5 , P T Wan BSc 5 , Kelly Lam MSc 5 , Ian Ck Wong PhD, FRCPCH(Hon) 6 7 , Janette Kwok PhD, FHKAM(Path) 8 , Marco Hk Ho MD, FRCP 1 , Godfrey Cf Chan MD, FRCPCH(UK) 1 , Yu Lung Lau MD(Hon), FRCPCH 1 , Patrick Ip MPH, FRCPCH(UK) 1 , Mike Yw Kwan MSc(Applied Epidemiology) CUHK, FHKAM(Paed) 2



Background: Pediatric COVID-19 studies exploring the relationships between NPS and saliva viral loads, clinical and immunological profiles are lacking.
Methods: Demographics, immunological profiles, nasopharyngeal swab (NPS), and saliva samples collected on admission, and hospital length of stay (LOS) were assessed in children below 18 years with COVID-19.
Findings: 91 patients were included between March and August 2020. NPS and saliva viral loads were correlated (r=0.315, p=0.01). Symptomatic patients had significantly higher NPS and saliva viral loads than asymptomatic patients. Serial NPS and saliva viral load measurements showed that the log10 NPS (r=-0.532, p<0.001) and saliva (r=-0.417, p<0.001) viral loads for all patients were inversely correlated with the days from symptom onset with statistical significance. Patients with cough, sputum, and headache had significantly higher saliva, but not NPS, viral loads. Higher saliva, but not NPS, viral loads were associated with total lymphopenia, CD3 and CD4 lymphopenia (all p<0.05), and were inversely correlated with total lymphocyte (r=-0.43), CD3 (r=-0.55), CD4 (r=-0.60), CD8 (r=-0.41), B (r=-0.482), and NK (r=-0.416) lymphocyte counts (all p<0.05). Interpretation: Saliva viral loads on admission in children correlated better with clinical and immunological profiles than NPS.