It is time to acknowledge coronavirus transmission via frozen and chilled foods: Undeniable evidence from China and lessons for the world.

Since the broke out of the novel coronavirus disease at the end of 2019, nearly 650 million people have been infected around the globe, and >6.6 million have died from this disease. The first wave of infections in mainland China had been effectively controlled within a short period, with no domestic cases of infection for 56 consecutive days from April 16, 2020. Nonetheless, the re-emergence of several outbreaks in multiple Chinese cities posed a new challenge for public health authorities after new cases of infections were found in Xinfadi Market in Beijing on June 11, 2020. In the following series of re-emergent outbreaks, findings from epidemiological investigations suggested that more than twenty re-emergent outbreaks were caused by fomite transmission, predominantly via imported frozen and chilled foods contaminated by the SARS-CoV-2 virus. Seven of the eleven incidents involving frozen and chilled foods were identified by screening individuals with occupational exposure to imported cold-chain foods and associated individuals. Evidence showed that low temperatures and poor ventilation typically maintained through cold-chain logistics create amenable environments for the survival of SARS-CoV-2, making transnational cold chain logistics a congenial vehicle to spread the virus through global transport of consumer goods. To address this gap, here we present a scrutiny of the findings from epidemiological investigations in recent re-emergent outbreaks in China caused by fomite transmission via imported foods and goods. A national regime of traceable cold-chain foods and reinforced customs inspection protocols were established by public health authorities in mainland China as emergency responses to recurring outbreaks from fomite transmission via imported goods. We urge that more attention needs to be given to this specific route of pathogenic transmission to ensure biosecurity and to increase the preparedness for epidemic or pandemic scenarios by the global food industry and logistics carriers.

Investigating the microbial inactivation effect of low temperature high pressure carbon dioxide and its application in frozen prawn (Penaeus vannamei).

During the pandemic of coronavirus disease 2019, the fact that frozen foods can carry the relevant virus raises concerns about the microbial safety of cold-chain foods. As a non-thermal processing technology, high pressure carbon dioxide (HPCD) is a potential method to reduce microbial load on cold-chain foods. In this study, we explored the microbial inactivation of low temperature (5-10 °C) HPCD (LT-HPCD) and evaluated its effect on the quality of prawn during freeze-chilled and frozen storage. LT-HPCD treatment at 6.5 MPa and 10 °C for 15 min could effectively inactivate E. coli (99.45%) and S. aureus (94.6%) suspended in 0.85% NaCl, SARS-CoV-2 Spike pseudovirus (>99%) and human coronavirus 229E (hCoV-229E) (>1-log virus tilter reduction) suspended in DMEM medium. The inactivation effect of LT-HPCD was weakened but still significant when the microorganisms were inoculated on the surface of food or package. LT-HPCD treatment at 6.5 MPa and 10 °C for 15 min achieved about 60% inactivation of total aerobic count while could maintain frozen state and quality of prawn. Moreover, LT-HPCD treated prawn exhibited significant slower microbial proliferation and no occurrence of melanosis compared with the untreated samples during chilled storage. A comprehensive quality investigation indicated that LT-HPCD treatment could maintain the color, texture and sensory of prawn during chilled or frozen storage. Consequently, LT-HPCD could improve the microbial safety of frozen prawn while maintaining its original quality, and could be a potential method for food industry to improve the microbial safety of cold-chain foods.

COVID-19 Outbreaks Linked to Imported Frozen Food in China: Status and Challege.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA contamination was reported on China's imported frozen foods and packaging materials. However, there was no evidence of this disease initiated by environment-to-human transmission until the outbreak of coronavirus disease 2019 (COVID-19) in Beijing in June 2020. This article aimed to analyze and summarize COVID-19 outbreaks related to cold-chain foods to provide a scientific basis for tracing the epidemiological trajectory of the pandemic, providing risk assessments, and mitigation policies. Overall, 37 COVID-19 outbreaks and 5,741 infected cases were reported within the study period. It was found that 7 outbreaks and 689 cases were linked to imported frozen foods. The first index case among the 7 outbreaks was exposed to SARS-CoV-2-contaminated outer packaging of frozen food, triggering the subsequent community transmission. This study supported the speculation that cold-chain foods act as a pathway for SARS-CoV-2 and might present a risk for virus transmission between countries and regions. Handlers and processors exposed to the imported frozen foods should be effectively self-protected, daily monitored for clinical manifestations of COVID-19, and tested for SARS-CoV-2 nucleic acid at regular intervals.

Microbiological analysis of frozen profiteroles and mini chocolate eclairs implicated in a national salmonellosis outbreak.

Between November 2018 and May 2019, Canada experienced a nationwide salmonellosis outbreak linked to the presence of Salmonella enterica ser. Enteritidis in frozen profiteroles. Analysis of the implicated food products revealed low levels of Salmonella ranging from 0.2 to 0.7 MPN/100g. Water activity and pH of the food samples ranged from 0.9479 to 0.9867 and 4.6-6.8 respectively indicating conditions conducive to bacterial growth. Higher levels of the hygiene indicators Enterobacteriaceae and coliforms were associated with Salmonella positive samples compared to Salmonella negative samples. Investigation of the relationship between storage conditions, temperature, and pathogen levels during thawing revealed that the profiteroles reached temperatures permissive to pathogen growth (≥5 °C) much sooner than pathogen growth was observed and that the composition of the food matrix can influence bacterial levels upon thawing. Collectively these data can be used to inform guidance to minimize the risk of infection from the consumption of contaminated cream-filled frozen desserts.

Cold-chain transportation in the frozen food industry may have caused a recurrence of COVID-19 cases in destination: Successful isolation of SARS-CoV-2 virus from the imported frozen cod package surface.

Coronavirus disease 2019 (COVID-19) pandemic has spread in 220 countries/regions to wreak havoc to human beings around the world. At present, the second wave of COVID-19 has begun in many European countries. The complete control of COVID-19 is very urgent. Although China quickly brought the virus under control, there have been eight sporadic outbreaks in China since then. Both in Xinfadi of Beijing and Dalian outbreak of COVID-19, environmental swab samples related to imported cold chain food were tested nucleic acid positive for SARS-CoV-2. In this outbreak in Qingdao, we directly isolated SARS-CoV-2 from the cod outer package's surface swab samples. This is the first time worldwide, SARS-CoV-2 were isolated from the imported frozen cod outer package's surface, which showed that imported frozen food industry could import SARS-CoV-2 virus.