Exhaled SARS-CoV-2 RNA viral load kinetics measured by facemask sampling associates with household transmission

Pan, Daniel, Williams, Caroline M., Decker, Jonathan ORCID: 0000-0001-5904-7311, Fletcher, Eve, Sze, Shirley, Assadi, Sara, Haigh, Richard, Saleem, Baber, Nazareth, Joshua, Garton, Natalie J., Pareek, Manish and Barer, Michael R. (2023) Exhaled SARS-CoV-2 RNA viral load kinetics measured by facemask sampling associates with household transmission. Clinical Microbiology and Infection, 29 (2). 254.e1-254.e6. doi:10.1016/j.cmi.2022.07.005

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Abstract

Objectives No studies have examined longitudinal patterns of naturally exhaled SARS-CoV-2 RNA viral load (VL) during acute infection. We report this using facemask sampling (FMS) and assessed the relationship between emitted RNA VL and household transmission. Methods Between December 2020 and February 2021, we recruited participants within 24 hours of a positive RT-qPCR on upper respiratory tract sampling (URTS) (day 0). Participants gave FMS (for 1 hour) and URTS (self-taken) on seven occasions up to day 21. Samples were analysed by RT-qPCR (from sampling matrix strips within the mask) and symptom diaries were recorded. Household transmission was assessed through reporting of positive URTS RT-qPCR in household contacts. Results Analysis of 203 FMS and 190 URTS from 34 participants showed that RNA VL peaked within the first 5 days following sampling. Concomitant URTS, FMS RNA VL, and symptom scores, however, were poorly correlated, but a higher severity of reported symptoms was associated with FMS positivity up to day 5. Of 28 participants who had household contacts, 12 (43%) reported transmission. Frequency of household transmission was associated with the highest (peak) FMS RNA VL obtained (negative genome copies/strip: 0% household transmission; 1 to 1000 copies/strip: 20%; 1001 to 10 000 copies/strip: 57%; >10 000 copies/strip: 75%; p = 0.048; age adjusted OR of household transmission per log increase in copies/strip: 4.97; 95% CI, 1.20–20.55; p = 0.02) but not observed with peak URTS RNA VL. Discussion Exhaled RNA VL measured by FMS is highest in early infection, can be positive in symptomatic patients with concomitantly negative URTS, and is strongly associated with household transmission.

Item Type:	Article
Article Type:	Article
Uncontrolled Keywords:	Airborne; Transmission; SARS-CoV-2; COVID-19; Viral load; Exhaled virus; Viral diagnostics; Respiratory viruses; Nasopharyngeal sampling; Facemask sampling
Subjects:	Q Science > QR Microbiology > QR355 Virology
Divisions:	Schools and Research Institutes > School of Health and Social Care
Research Priority Areas:	Health, Life Sciences, Sport and Wellbeing
Depositing User:	Jonathan Decker
Date Deposited:	04 Sep 2023 09:37
Last Modified:	04 Sep 2023 10:13
URI:	https://eprints.glos.ac.uk/id/eprint/13066

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