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Reduced pathogenicity of the SARS-CoV-2 omicron variant in hamsters.
McMahan, Katherine; Giffin, Victoria; Tostanoski, Lisa H; Chung, Benjamin; Siamatu, Mazuba; Suthar, Mehul S; Halfmann, Peter; Kawaoka, Yoshihiro; Piedra-Mora, Cesar; Jain, Neharika; Ducat, Sarah; Kar, Swagata; Andersen, Hanne; Lewis, Mark G; Martinot, Amanda J; Barouch, Dan H.
  • McMahan K; Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA, USA.
  • Giffin V; Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA, USA.
  • Tostanoski LH; Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA, USA.
  • Chung B; Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA, USA.
  • Siamatu M; Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA, USA.
  • Suthar MS; Emory Vaccine Center, Emory School of Medicine, Atlanta, GA, USA.
  • Halfmann P; Influenza Research Institute, University of Wisconsin, Madison, WI 53711, USA.
  • Kawaoka Y; Influenza Research Institute, University of Wisconsin, Madison, WI 53711, USA.
  • Piedra-Mora C; Tufts University Cummings School of Veterinary Medicine, North Grafton, MA, USA.
  • Jain N; Tufts University Cummings School of Veterinary Medicine, North Grafton, MA, USA.
  • Ducat S; Tufts University Cummings School of Veterinary Medicine, North Grafton, MA, USA.
  • Kar S; Bioqual, Rockville, MD 20852, USA.
  • Andersen H; Bioqual, Rockville, MD 20852, USA.
  • Lewis MG; Bioqual, Rockville, MD 20852, USA.
  • Martinot AJ; Tufts University Cummings School of Veterinary Medicine, North Grafton, MA, USA.
  • Barouch DH; Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA, USA.
Med (N Y) ; 3(4): 262-268.e4, 2022 04 08.
Article in English | MEDLINE | ID: covidwho-1829236
ABSTRACT

Background:

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron (B.1.1.529) variant has proven to be highly transmissible and has outcompeted the Delta variant in many regions of the world. Early reports have also suggested that Omicron may result in less severe clinical disease in humans. Here, we show that Omicron is less pathogenic than prior SARS-CoV-2 variants in Syrian golden hamsters.

Methods:

Hamsters were inoculated with either SARS-CoV-2 Omicron or other SARS-CoV-2 variants. Animals were followed for weight loss, and upper and lower respiratory tract tissues were assessed for viral loads and histopathology.

Findings:

Infection of hamsters with the SARS-CoV-2 WA1/2020, Alpha, Beta, or Delta strains led to 4%-10% weight loss by day 4 and 10%-17% weight loss by day 6. In contrast, infection of hamsters with two different Omicron challenge stocks did not result in any detectable weight loss, even at high challenge doses. Omicron infection led to substantial viral replication in both the upper and lower respiratory tracts but demonstrated lower viral loads in lung parenchyma and reduced pulmonary pathology compared with WA1/2020 infection.

Conclusions:

These data suggest that the SARS-CoV-2 Omicron variant may result in robust upper respiratory tract infection, but less severe lower respiratory tract clinical disease, compared with prior SARS-CoV-2 variants.

Funding:

Funding for this study was provided by NIH grant CA260476, the Massachusetts Consortium for Pathogen Readiness, the Ragon Institute, and the Musk Foundation.
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Full text: Available Collection: International databases Database: MEDLINE Main subject: SARS-CoV-2 / COVID-19 Type of study: Prognostic study Topics: Variants Limits: Animals Language: English Journal: Med (N Y) Year: 2022 Document Type: Article Affiliation country: J.medj.2022.03.004

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Full text: Available Collection: International databases Database: MEDLINE Main subject: SARS-CoV-2 / COVID-19 Type of study: Prognostic study Topics: Variants Limits: Animals Language: English Journal: Med (N Y) Year: 2022 Document Type: Article Affiliation country: J.medj.2022.03.004