COVID-19 Outbreak Caused by Contaminated Packaging of Imported Cold-Chain Products - Liaoning Province, China, July 2020

Abstract

What is known about this topic?

Few major outbreaks of coronavirus disease 2019 (COVID-19) have occurred in China after major non-pharmaceutical interventions and vaccines have been deployed and implemented. However, sporadic outbreaks that had high possibility to be linked to cold chain products were reported in several cities of China..

What is added by this report?

In July 2020, a COVID-19 outbreak occurred in Dalian, China. The investigations of this outbreak strongly suggested that the infection source was from COVID-19 virus-contaminated packaging of frozen seafood during inbound unloading personnel contact.

What are the implications for public health practice?

Virus contaminated paper surfaces could maintain infectivity for at least 17-24 days at -25 ℃. Exposure to COVID-19 virus-contaminated surfaces is a potential route for introducing the virus to a susceptible population. Countries with no domestic transmission of COVID-19 should consider introducing prevention strategies for both inbound travellers and imported goods. Several measures to prevent the introduction of the virus via cold-chain goods can be implemented.

Keywords: COVID-19; SARS-CoV-2-contaminated packaging; imported cold-chain products; outbreak.

Figure 1

Investigation workflow and the Dalian COVID-19 outbreak. Imported cold-chain seafood products with COVID-19 virus infected wharf workers and then were introduced into the seafood product workshop of Company K before spreading further. The epidemiological investigation strategy was shown bolded in blue. COVID-19 case data were represented by a grey dotted box, and virus introduction from the DK ship was represented by a blue dotted box.

Figure 2

Phylogenetic tree based on Dalian outbreak-related samples. (A) Phylogenetic tree based on the representative full-length genome sequences of the COVID-19 virus. The genomes of the COVID-19 virus from Dalian case samples were highlighted in yellow, environmental samples from cold-chain seafood processing work area of Company K were highlighted in green and pollock packaging samples were highlighted in blue. The genome of the reference COVID-19 virus from Wuhan in December 2019 was shaded in grey. Strains associated with specific outbreaks in China were indicated by blue squares. The PANGO lineages were marked and colored on the right. The tree was rooted using strain WH04 (EPI_ISL_406801) in accord with the root of PANGO tree. (B) Phylogenetic tree based on the full-length genome sequences of Dalian COVID-19 virus samples, rooted using the Wuhan reference strain.