Hamsters immunized with formalin-inactivated SARS-CoV-2 develop accelerated lung histopathological lesions and Th2-biased response following infection.

Publication date: Jul 04, 2025

One of the concerns regarding vaccine safety during the COVID-19 pandemic was the potential manifestation of vaccine-associated enhancement of disease (VAED) upon SARS-CoV-2 infection. To investigate the suitability of the Syrian hamster model to test for VAED, we immunized animals with an experimental formaldehyde-inactivated, alum-adjuvanted SARS-CoV-2 vaccine preparation. In two independent experiments, challenge infection did not result in an enhancement of the clinical disease in vaccinated animals compared with mock-vaccinated animals. However, at early timepoints (2-5 days) post-challenge, lung histopathology progressed faster and was more prominent in vaccinated hamsters and lung tissue showed elevated mRNA levels of IL-4 and IL-13. At later time points, cytokine responses and lung pathology were comparable between vaccinated and mock-vaccinated hamsters, underscoring the transient nature of the pathological aggravation. With this work we show that the Syrian hamster model can be used to assess possible vaccine safety considerations in a preclinical setting.

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Concepts Keywords
Formaldehyde Cov
Hamster Enhancement
Inactivated Hamster
Pathology Hamsters
Vaccines Immunized
Inactivated
Infection
Lung
Mock
Safety
Sars
Syrian
Vaccinated
Vaccine
Vaed

Semantics

Type Source Name
drug DRUGBANK Formaldehyde
disease MESH infection
disease MESH COVID-19 pandemic
pathway REACTOME SARS-CoV-2 Infection
drug DRUGBANK Binetrakin
disease IDO pathogen
disease MESH measles
pathway KEGG Measles
disease IDO immune response
disease IDO process
drug DRUGBANK Aluminum hydroxide
drug DRUGBANK Esomeprazole
pathway KEGG Viral replication
disease MESH hypersensitivity
drug DRUGBANK Trestolone
disease MESH weight loss
disease IDO replication
disease MESH inflammation
drug DRUGBANK Coenzyme M
disease IDO assay

Original Article

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