There have been suggestions that the new domestic COVID-19 cases in New Zealand were the result of samples of the SARS-CoV-2 virus surviving on food packaging.
Dr Julian Tang, Honorary Associate Professor in Respiratory Sciences, University of Leicester, said:
“Laboratory-based studies on the survival of the SARS-CoV-2 virus certainly show that the virus can survive for hours to days on some packaging materials – mostly cardboard and various forms of plastic:
“The transmission risk being based on the usual assumption that workers in the food packaging plants will touch these surfaces then self-inoculate via their nose, mouth, eyes, though this has actually not been shown definitively for SARS-CoV-2 yet.
“The problem with these ‘ideal’ studies is that the environmental conditions will change rapidly in the real-life environments that such food packages pass through, which may reduce the virus survival further compare to these lab-based ‘constant’ exposure conditions.
“This surface packaging transmission source/route is also difficult to be definitive about because there is a need to exclude any recent exposure from any other source (e.g. asymptomatic social contacts or household cases via conversational aerosols) to be sure that any food packaging-related exposure/infection is the true cause of their infections. Nowadays, this will need additional careful viral sequencing and analysis to check this – which may show differences between the imported SARS-CoV-2 on the packaging versus the locally circulating SARS-CoV-2. Such studies may be ongoing in New Zealand and China to determine this – but see the caveat below.
“This transmission route from contaminated surfaces to fingers to mouth/nose/eyes – the fomite/contact transmission route, is not considered the main route of transmission for SARS-CoV-2 now: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/how-covid-spreads.html
“And any clusters of COVID-19 cases in such food warehouses need to be careful to exclude any transmission between infected individuals via other transmission routes – like person-to-person aerosols, which may also transmit the same imported virus between warehouse workers. This could confound such viral sequencing/analysis studies if the food packaging source is assumed to be the only source that could have given rise to COVID-19 cases amongst these workers.”
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