Omicron Variant Generates a Higher and More Sustained Viral Load in Nasopharynx and Saliva Than the Delta Variant of SARS-CoV-2

Beathe K Granerud; Thor Ueland; Andreas Lind; Arne Søraas; Børre Fevang; Anne Katrine Steffensen; Huda Al-Baldawi; Fridtjof Lund-Johansen; Pål Aukrust; Bente Halvorsen; Tuva B Dahl; Susanne Dudman; Fredrik Müller; Jan Cato Holter

doi:10.3390/v14112420

Omicron Variant Generates a Higher and More Sustained Viral Load in Nasopharynx and Saliva Than the Delta Variant of SARS-CoV-2

Viruses. 2022 Oct 31;14(11):2420. doi: 10.3390/v14112420.

Authors

Beathe K Granerud^{1

2}, Thor Ueland^{1

3

4}, Andreas Lind², Arne Søraas², Børre Fevang^{3

5}, Anne Katrine Steffensen^{1

2}, Huda Al-Baldawi¹, Fridtjof Lund-Johansen^{6

7}, Pål Aukrust^{1

3

4

5}, Bente Halvorsen^{1

3}, Tuva B Dahl^{3

8}, Susanne Dudman^{1

2}, Fredrik Müller^{1

2}, Jan Cato Holter^{1

2}

Affiliations

¹ Institute of Clinical Medicine, University of Oslo, 0316 Oslo, Norway.
² Department of Microbiology, Oslo University Hospital, 0424 Oslo, Norway.
³ Research Institute of Internal Medicine, Oslo University Hospital, 0424 Oslo, Norway.
⁴ K.G. Jebsen Thrombosis Research and Expertise Center, Faculty of Health Sciences, University of Tromsø, 6050 Tromsø, Norway.
⁵ Section of Clinical Immunology and Infectious Diseases, Oslo University Hospital, 0424 Oslo, Norway.
⁶ Department of Immunology, Oslo University Hospital, 0424 Oslo, Norway.
⁷ ImmunoLingo Convergence Centre, University of Oslo, 0316 Oslo, Norway.
⁸ Division of Critical Care and Emergencies, Oslo University Hospital, 0424 Oslo, Norway.

Abstract

The Omicron variant of SARS-CoV-2 spreads more easily than earlier variants, possibly as a result of a higher viral load in the upper respiratory tract and oral cavity. Hence, we investigated whether the Omicron variant generates a higher viral load than that of the Delta variant in saliva and nasopharynx. Both specimens were collected from 52 Omicron and 17 Delta cases at two time points one week apart and analyzed by qRT-PCR. Viral load was measured as 10 log RNA genome copies per 1000 human cells according to the WHO reference standard. We found that Omicron cases carried a higher viral load and had more sustained viral shedding compared to the Delta cases, especially in the nasopharynx.

Keywords: Delta variant; Norway; Omicron variant; SARS-CoV-2; viral load.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

COVID-19*
Humans
Nasopharynx / virology
RNA, Viral / analysis
RNA, Viral / genetics
SARS-CoV-2 / genetics
Saliva* / virology
Viral Load

Substances

RNA, Viral

Supplementary concepts

SARS-CoV-2 variants

Grants and funding

This research was funded by Oslo University Hospital through a grant from the Coalition for Epidemic Preparedness Innovations, the Research Council of Norway (no. 312780) and a philanthropic donation from Vivaldi Invest A/S, which is owned by Jon Stephenson von Tetzchner.