How to deal with the transmission of SARS-COV-2 on the surface of Cold-chain foods to people: a review

A narrative review of alternative transmission routes of COVID 19: what we know so far

The Coronavirus disease 19 (COVID-19) pandemics, caused by severe acute respiratory syndrome coronaviruses, SARS-CoV-2, represent an unprecedented public health challenge. Beside person-to-person contagion via airborne droplets and aerosol, which is the main SARS-CoV-2's route of transmission, alternative modes, including transmission via fomites, food and food packaging, have been investigated for their potential impact on SARS-CoV-2 diffusion. In this context, several studies have demonstrated the persistence of SARS-CoV-2 RNA and, in some cases, of infectious particles on exposed fomites, food and water samples, confirming their possible role as sources of contamination and transmission. Indeed, fomite-to-human transmission has been demonstrated in a few cases where person-to-person transmission had been excluded. In addition, recent studies supported the possibility of acquiring COVID-19 through the fecal-oro route; the occurrence of COVID-19 gastrointestinal infections, in the absence of respiratory symptoms, also opens the intriguing possibility that these cases could be directly related to the ingestion of contaminated food and water. Overall, most of the studies considered these alternative routes of transmission of low epidemiological relevance; however, it should be considered that they could play an important role, or even be prevalent, in settings characterized by different environmental and socio-economic conditions. In this review, we discuss the most recent findings regarding SARS-CoV-2 alternative transmission routes, with the aim to disclose what is known about their impact on COVID-19 spread and to stimulate research in this field, which could potentially have a great impact, especially in low-resource contexts.

Viral Cultures for Assessing Fomite Transmission of SARS-CoV-2: a Systematic Review and Meta-Analysis

Background

The role of fomites in the transmission of SARS-CoV-2 is unclear.

Aim

To assess whether SARS-CoV-2 can be transmitted through fomites, using evidence from viral culture studies.

Methods

Searches were conducted in the World Health Organization COVID-19 Database, PubMed, LitCovid, medRxiv, and Google Scholar to December 31^st, 2021. Studies that investigated fomite transmission and performed viral culture to assess the cytopathic effect (CPE) of positive fomite samples and confirmation of SARS-CoV-2 as the cause of the CPE were included. The risk of bias using a checklist modified from the modified Quality Assessment of Diagnostic Accuracy Studies – 2 (QUADAS-2) criteria was assessed.

Findings

Twenty-three studies were included. The overall risk of bias was moderate. Five studies demonstrated replication-competent virus from fomite cultures and three used genome sequencing to match fomite samples with human clinical specimens. The mean cycle threshold (C_T) of samples with positive viral culture was significantly lower compared with cultured samples that returned negative results (standardized mean difference: –1.45; 95% confidence interval (CI): –2.00 to –0.90; I² = 0%; P < 0.00001). The likelihood of isolating replication-competent virus was significantly greater when C_T was <30 (relative risk: 3.10; 95% CI: 1.32 to 7.31; I² = 71%; P = 0.01). Infectious specimens were mostly detected within seven days of symptom onset. One study showed possible transmission of SARS-CoV-2 from fomites to humans.

Conclusion

The evidence from published studies suggests that replication-competent SARS-CoV-2 is present on fomites. Replication-competent SARS-CoV-2 is significantly more likely when the PCR C_T for clinical specimens and fomite samples is <30. Further studies should investigate the duration of infectiousness of SARS-CoV-2 and the frequency of transmission from fomites.

The governance of imported 2019-nCov infections: What can be learned from China's experience?

Delta and Omicron variants of 2019-nCoV are still spreading globally, and many imported infections have been identified in China as well. In order to control the spread chain from imported to local, China has implemented the dynamic Covid-zero policy. In this article we summarized China's governance models and practices of fighting potential imported infections in two directions. One targets at international travelers, which can be outlined as four lines of defense: customs epidemic prevention, quarantine upon arrival, relevant laws and regulations, and community tracking. The other is against other vectors potentially carrying 2019-nCoV, which can be outlined by three lines of defense: customs epidemic prevention, disinfection and personal protection, and information management. However, there are still some challenges that are yet to be addressed, such as illegal immigration, accidental occupational exposure to 2019-nCoV, etc. China's experience indicates that no country can stay safe during the global pandemic as long as there are local outbreaks in other countries, and active prevention and control measures based on science and a complete set of laws and regulations are still necessary at current stage. What's more, accountable government commitment and leadership, strengthened health and social governance systems, and whole society participation are required. It is suggested that the global community continue to closely cooperate together and take active rather than passive actions to block the potential imported 2019-nCoV from causing local spreading.