Damn Hamsters! (New Lancet study on Delta variant)

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Eric Topol
@EricTopol
One of the major theories for Omicron's evolution is via an animal reservoir. Here is a new report of "2 separate [Delta] transmission events [from pet hamsters] to humans are documented, one leading to onward household spread."
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4017393…
1:33 PM · Jan 28, 2022

Abstract

Background: Transmission of SARS-CoV-2 from humans to other mammals, including pet animals, has been reported. However, with the exception of farmed mink, there is no previous documentation that these infected animals can infect humans, nor of further onward spread among humans. Following a confirmed SARS-CoV-2 infection of a pet store worker, animals in the store and the warehouse supplying it were tested for evidence of SARS-CoV-2 infection.

Methods: Viral swabs and blood samples from pet animals were collected in a pet shop and the warehouse supplying it and tested by SARS-CoV-2 RT-PCR and serological assays, respectively. SARS-CoV-2 RT-PCR positive samples were studied by full genome sequencing analysis.

Findings: Over 50% of individually tested Syrian hamsters in the pet shop (8/16) and warehouse (7/12) were positive for SARS-CoV-2 infection in RT-PCR or serological tests. None of dwarf hamsters (n=77), rabbits (n=246), Guinea pigs (n=66), chinchilla (n=116) and mice (n=2) were confirmed positive in RT-PCR tests. SARS-CoV-2 viral genomes deduced from human and hamster cases in this incident all belong to Delta variant of concern (AY.127) that had not been circulating locally prior. These sequences are highly similar, but distinct. The viral genomes obtained from hamsters are phylogenetically related with some sequence heterogeneity and phylogenetic dating suggest infection in these hamsters occurred around 21 November 2021. Two separate transmission events to humans are documented, one leading to onward household spread.

Interpretation: Pet hamsters can be naturally infected in “real-life” settings. The virus can circulate within hamsters and lead to human infections. Both genetic and epidemiological results strongly suggest that there were two independent hamster-to-human transmission and that such events can lead to onward human transmission. Importation of infected hamsters was the most likely source of virus infection.

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