Low risk of environmental contagion by SARS-CoV-2 in non-sanitary spaces.

OBJECTIVE: To study the presence of SARS-CoV-2 on surfaces (high, medium and low contact) and airs in non-sanitary spaces with high public influx to evaluate the risk of environmental contagion. METHODS: Surfaces and airs were analysed by RT-qPCR to detect the presence of SARS-CoV-2. RESULTS: 394 surfaces and air samples were obtained from spaces with high public influx such as offices, shopping centres and nursing homes. The virus was not detected in any of the samples analysed. CONCLUSION: Although we cannot emphatically conclude that there is no risk of environmental 27 infection by SARS-CoV-2 in non-sanitary spaces, we can affirm that the risk is almost non- existent.

Stability and transmissibility of SARS-CoV-2 in the environment.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing the ongoing global coronavirus disease 2019 (COVID-19) pandemic, is believed to be transmitted primarily through respiratory droplets and aerosols. However, reports are increasing regarding the contamination of environmental surfaces, shared objects, and cold-chain foods with SARS-CoV-2 RNA and the possibility of environmental fomite transmission of the virus raises much concern and debate. This study summarizes the current knowledge regarding potential mechanisms of environmental transmission of SARS-CoV-2, including the prevalence of surface contamination in various settings, the viability and stability of the virus on surfaces or fomites, as well as environmental factors affecting virus viability and survival such as temperature and relative humidity. Instances of fomite transmission, including cold-chain food transmission, and the importance of fomite transmission in epidemics, are discussed. The knowledge gaps regarding fomite transmission of SARS-CoV-2 are also briefly analyzed.

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.

COVID-19 and Food Safety

Concerns over whether people can be infected with SARS-CoV-2 from food and packaging have caused significant disruption to global food trade. SARS-CoV-2, the virus that causes COVID-19, can remain infectious and detectable on packaging or some foods under certain cold-chain conditions. However, there is minimal evidence that people have been infected with SARS-CoV-2 from packaging or from foodborne transmission. Cooking of food will inactivate the virus. Any infectious SARS-CoV-2 present in consumed food would likely be inactivated by stomach acid. Nonetheless, good food hygiene practices are sensible precautions to minimize any possibility of food or packaging acting as a vector for SARS-CoV-2.

The propensity of fomite spread of SARS-CoV-2 virus through produce supply chain.

Background: The global community has battled the spread of SAR-CoV-2 for almost 2 years, and the projection is that the virus may be recurrent like the seasonal flu. The SARS-CoV-2 pandemic disrupted activities within the food supply chain that cost billions of dollars globally. This has heightened concerns about fomite spread of the virus through surfaces. There is an urgent need to understand the risk portends by this virus along the produce supply chain with conditions (low temperature and high relative humidity) conducive to extended survival of the virus. Main body: Pre-dating SARS-CoV-2 are other types of coronaviruses that had lower infection and mortality rates. There are some similarities between the former and the new coronavirus, especially with regards to transmission modes and their survivability on surfaces. There is evidence of other coronaviruses' survival on surfaces for weeks. Currently, there are limited evidence-based studies to enlighten us on how the virus is transmitted within the produce supply chain. A few studies claim that the virus could spread through the cold supply chains. However, these are not sufficient to make a conclusive inference about the deadly SARS-CoV-2. Conclusions: This paper provides a succinct review of the literature on current understanding of the transmission, survivability, and risk SARS-CoV-2 portend to humans within the produce supply chain and calls for more evidence-based research to allay or alert us of the potential risk of fomite transmission of SARS-CoV-2. The paper also highlights examples of conventional and novel non-thermal inactivation and sanitation methods applicable to this type of virus.

Low Risk of Severe Acute Respiratory Syndrome Coronavirus 2 Transmission by Fomites: A Clinical Observational Study in Highly Infectious Coronavirus Disease 2019 Patients.

BACKGROUND: The contribution of droplet-contaminated surfaces for virus transmission has been discussed controversially in the context of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic. More importantly, the risk of fomite-based transmission has not been systematically addressed. Therefore, the aim of this study was to evaluate whether confirmed hospitalized coronavirus disease 2019 (COVID-19) patients can contaminate stainless steel carriers by coughing or intensive moistening with saliva and to assess the risk of SARS-CoV-2 transmission upon detection of viral loads and infectious virus in cell culture. METHODS: We initiated a single-center observational study including 15 COVID-19 patients with a high baseline viral load (cycle threshold value ≤25). We documented clinical and laboratory parameters and used patient samples to perform virus culture, quantitative polymerase chain reaction, and virus sequencing. RESULTS: Nasopharyngeal and oropharyngeal swabs of all patients were positive for viral ribonucleic acid on the day of the study. Infectious SARS-CoV-2 could be isolated from 6 patient swabs (46.2%). After coughing, no infectious virus could be recovered, however, intensive moistening with saliva resulted in successful viral recovery from steel carriers of 5 patients (38.5%). CONCLUSIONS: Transmission of infectious SARS-CoV-2 via fomites is possible upon extensive moistening, but it is unlikely to occur in real-life scenarios and from droplet-contaminated fomites.

Interventions to prevent surface transmission of an infectious virus based on real human touch behavior: a case study of the norovirus.

OBJECTIVES: Infectious viruses (e.g., SARS-CoV-2, norovirus) can transmit through surfaces. Norovirus has infected millions of individuals annually. Interventions on norovirus transmission in high-risk indoor environment are important. METHODS: This study focused on a restaurant in Guangzhou, China. More than 41,000 touches by both diners and staff members were collected using video cameras. A surface transmission model was developed and combined with these real human touch behaviors to analyze the effectiveness of different norovirus prevention strategies. RESULTS: When the virus carrier was a diner, the virus intake fraction of diners in the same table was the highest. Increasing the touch frequency on personal private surfaces would reduce the virus exposure. The virus intake fraction was reduced by 18.4% on average if public surfaces were not touched. Optimization on surface materials could reduce the virus intake fraction by 86.6%. Additionally, disinfecting tablecloths, clothes of diners, and chairs were the three most effective surface disinfection strategies. CONCLUSION: Controlling human touch behavior (e.g., reducing the self-touches on mucous membranes) is more effective than surface disinfection in controlling norovirus transmission, but surface disinfection cannot be ignored because human behavior is difficult to be controlled.

Efficiency of Quaternary Ammonium Disinfectants against SARS-CoV-2 and Coronavirus 229E

Background. The recent pandemic of CoVid19 has increased our need to assess the impact of disinfectants on the inactivation of human coronaviruses. The goals of this study were 1) quantify the disinfection of SARS-CoV-2 and human coronavirus 229 inactivations by various quaternary ammonium formulations, and 2) demonstrate the impact of disinfectants on preventing fomite-to-finger transfer of coronaviruses. Methods. We compared the inactivation of both SARS-Covid -2 and coronavirus 229E suspended in 5% fetal calf sera and dried on both metal and plastic surfaces. In addition, studies were conducted with a silinated quaternary ammonium compound that left a residual on the surface. Studies were also conducted on the finger transfer of coronavirus from various surfaces. The virus was allowed to dry on the surface for 30 minutes, then a transfer was conducted by placing the finger pad directly onto the contaminated surface. The finger was tested for the virus. The study was then repeated with virus-contaminated porcelain surfaces that were sprayed with a quaternary product or placed on a surface with a quaternary ammonium compound that left a residual. Results. Several readily available quaternary ammonium formulations were evaluated and proved to be effective with greater than a 99.9% reduction in titer after drying on both metal and plastic surfaces. In addition, a silinated quaternary ammonium compound that left a residual on the surface was capable of inactivating SARS-CoV-2 for at least seven days after application. Studies on the finger transfer of coronavirus from various surfaces showed that the amount of virus transfer to the finger varied from 0.46 to 49.0% depending upon the surface. Little or no virus transfer occurred from treated surfaces compared to the untreated controls. In addition, coronavirus 229E appears to be a good model for use in disinfection assessments for SARS-CoV-2. Conclusion. Our results demonstrate that various quaternary ammonium disinfectant formulations are effective against human coronaviruses. Finger transfer tests showed that transmission of coronavirus from surfaces can be prevented, reducing the risk of fomite transmission. Coronavirus 229E appears to be a good model for use in disinfection assessments for SARS-CoV-2.

Health and Safety Innovations to Reduce the Spread of Contagious Disease

In this paper, we report on a series of design innovation projects conducted by student teams at the University of Colorado at Denver in collaboration with research scientists at the US Air Force Research Lab. The COVID-19 pandemic has made apparent the risks of disease transmission through multiple vectors in public spaces that could potentially benefit from further protection and safety measures. Utilizing formal ideation and innovation methods from the 4D Design Innovation (DI) process, the teams studied what specific problems to solve, explored potential solution ideas, and developed some early-concept prototypes for feasibility demonstration. Design Innovation (DI) provides both an overall process for product design and also methods for each step in the process. This paper details the correlation between the steps in the DI process and the results produced by the teams. The teams primarily focused on minimizing the risk of disease transmission through reducing the physical touching of common public items;additional solutions relating to contact tracing and social distancing were also explored. Initial functional prototypes were developed and demonstrated for: (a) touchless elevator control systems using voice commands, foot pedals, gestures, and touchless buttons;(b) an automated desk usage hygienic management system;(c) an automated remote video person tracker for monitoring compliance with indoor social distancing and room capacity limits;and (d) a contact tracing app. We discuss the prototyped solutions in detail, and describe promising ways forward for developing these technologies, with the aims of combatting the spread of disease and ensuring overall public health, safety, and security. © 2021 IEEE.

A review on coronavirus survival on impermeable and porous surfaces

We review recent studies on fomite transmission of COVID-19, caused by the novel coronavirus. In particular, we focus on survival time of coronavirus on solid and porous surfaces. Since the aqueous phase of a respiratory droplet serves as a medium for virus survival, evaporation of the droplet on a surface plays a crucial role in determining the virus survival time. While the bulk of the droplet takes a few seconds to evaporate, previous virus titer measurements revealed that the virus can survive for several hours or days on a surface. This long survival of virus has been attributed to a residual thin-liquid film which remains after drying of the bulk droplet. The evaporation of the thin-film is governed by the disjoining pressure within it and therefore, is a much slower process which causes the virus to survive longer. However, the aforesaid disjoining pressure is significantly modulated for the case of porous surfaces due to their typical geometries. This accelerates the thin-film evaporation on porous surfaces and thereby making them lesser susceptible to virus survival. Therefore, porous materials are deemed to be relatively safer for mitigating the spread of COVID-19 via fomite transmission. Using results of the reported research, we briefly discuss the possible recommendations to mitigate the spread of the disease.

Predominant airborne transmission and insignificant fomite transmission of SARS-CoV-2 in a two-bus COVID-19 outbreak originating from the same pre-symptomatic index case.

The number of people infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to increase worldwide, but despite extensive research, there remains significant uncertainty about the predominant routes of SARS-CoV-2 transmission. We conducted a mechanistic modeling and calculated the exposure dose and infection risk of each passenger in a two-bus COVID-19 outbreak in Hunan province, China. This outbreak originated from a single pre-symptomatic index case. Some human behavioral data related to exposure including boarding and alighting time of some passengers and seating position and mask wearing of all passengers were obtained from the available closed-circuit television images/clips and/or questionnaire survey. Least-squares fitting was performed to explore the effect of effective viral load on transmission risk, and the most likely quanta generation rate was also estimated. This study reveals the leading role of airborne SARS-CoV-2 transmission and negligible role of fomite transmission in a poorly ventilated indoor environment, highlighting the need for more targeted interventions in such environments. The quanta generation rate of the index case differed by a factor of 1.8 on the two buses and transmission occurred in the afternoon of the same day, indicating a time-varying effective viral load within a short period of five hours.

Higher Concentrations of Bacterial Enveloped Virus Phi6 Can Protect the Virus from Environmental Decay.

Phage Phi6 is an enveloped virus considered a possible nonpathogenic surrogate for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other viral pathogens in transmission studies. Larger input amounts of bacteriophage Phi6 are shown to delay and protect the phage from environmental decay, both when the phages are dried in plastic tubes and when they are stored in saline solution at 4°C. In contrast, when bacteriophage Phi6 is placed in LB (Luria-Bertani) growth medium (instead of saline) prior to placement on the plastic surface, the influence of the starting concentration on viral recovery is negligible. Protection is reflected in the phage half-lives at higher concentrations being longer than the half-lives at lower concentrations. Because experiments supporting the possibility of fomite transmission of SARS-CoV-2 and other viruses rely upon the survival of infectious virus following inoculation onto various surfaces, large initial amounts of input virus on a surface may generate artificially inflated survival times compared to realistic lower levels of virus that a subject would normally encounter. This is not only because there are extra half-lives to go through at higher concentrations but also because the half-lives themselves are extended at higher virus concentrations. It is important to design surface drying experiments for pathogens with realistic levels of input virus and to consider the role of the carrier and matrix if the results are to be clinically relevant. IMPORTANCE During the coronavirus disease 2019 (COVID-19) pandemic, much attention has been paid to the environmental decay of SARS-CoV-2 due to the proposed transmission of the virus via fomites. However, published experiments have commenced with inocula with very high virus titers, an experimental design not representative of real-life conditions. The study described here evaluated the impact of the initial virus titer on the environmental decay of an enveloped virus, using a nonpathogenic surrogate for the transmission of SARS-CoV-2, enveloped bacteriophage Phi6. We establish that higher concentrations of virus can protect the virus from environmental decay, depending on conditions. This has important implications for stability studies of SARS-CoV-2 and other viruses. Our results point to a limitation in the fundamental methodology that has been used to attribute fomite transmission for almost all respiratory viruses.

Microstructured Surfaces for Reducing Chances of Fomite Transmission via Virus-Containing Respiratory Droplets.

Evaporation-induced particle aggregation in drying droplets is of significant importance in the prevention of pathogen transfer due to the possibility of indirect fomite transmission of the infectious virus particles. In this study, particle aggregation was directionally controlled using contact line dynamics (pinned or slipping) and geometrical gradients on microstructured surfaces by the systematic investigation of the evaporation process on sessile droplets and sprayed microdroplets laden with virus-simulant nanoparticles. Using this mechanism, we designed robust particle capture surfaces by significantly inhibiting the contact transfer of particles from fomite surfaces. For the proof-of-concept, interconnected hexagonal and inverted pyramidal microwall were fabricated using ultraviolet-based nanoimprint lithography, which is considered to be a promising scalable manufacturing process. We demonstrated the potentials of an engineered microcavity surface to limit the contact transfer of particle aggregates deposited with the evaporation of microdroplets by 93% for hexagonal microwall and by 96% for inverted pyramidal microwall. The particle capture potential of the interconnected microstructures was also investigated using biological particles, including adenoviruses and lung-derived extracellular vesicles. The findings indicate that the proposed microstructured surfaces can reduce the indirect fomite transmission of highly infectious agents, including norovirus, rotavirus, or SARS-CoV-2, via respiratory droplets.

Detection of SARS-CoV-2 on Surfaces in Households of Persons with COVID-19.

SARS-CoV-2 transmission from contaminated surfaces, or fomites, has been a concern during the COVID-19 pandemic. Households have been important sites of transmission throughout the COVID-19 pandemic, but there is limited information on SARS-CoV-2 contamination of surfaces in these settings. We describe environmental detection of SARS-CoV-2 in households of persons with COVID-19 to better characterize the potential risks of fomite transmission. Ten households with ≥1 person with laboratory-confirmed COVID-19 and with ≥2 members total were enrolled in Utah, U.S.A. Nasopharyngeal and anterior nasal swabs were collected from members and tested for the presence of SARS-CoV-2 by RT-PCR. Fifteen surfaces were sampled in each household and tested for presence and viability of SARS-CoV-2. SARS-CoV-2 RNA was detected in 23 (15%) of 150 environmental swab samples, most frequently on nightstands (4/6; 67%), pillows (4/23; 17%), and light switches (3/21; 14%). Viable SARS-CoV-2 was cultured from one sample. All households with SARS-CoV-2-positive surfaces had ≥1 person who first tested positive for SARS-CoV-2 ≤ 6 days prior to environmental sampling. SARS-CoV-2 surface contamination occurred early in the course of infection when respiratory transmission is most likely, notably on surfaces in close, prolonged contact with persons with COVID-19. While fomite transmission might be possible, risk is low.

SARS Wars: the Fomites Strike Back.

Controversy continues about the significance of fomite transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Recent papers continue to advocate concern. However, designs of studies showing virus survival on surfaces under laboratory conditions are unsuitable for extrapolation to real life. Although viral RNA is frequently found on real-life surfaces, actual tests for infectious virus are almost entirely negative, even in hospitals with COVID-19 patients. Fomite transmission should be regarded as no more than a very minor component of this pandemic.

Superhydrophobicity preventing surface contamination as a novel strategy against COVID-19.

Surface contact with virus is ubiquitous in the transmission pathways of respiratory diseases such as Coronavirus Disease 2019 (COVID-19), by which contaminated surfaces are infectious fomites intensifying the transmission of the disease. To date, the influence of surface wettability on fomite formation remains elusive. Here, we report that superhydrophobicity prevents the attachment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on surfaces by repelling virus-laden droplets. Compared to bare surfaces, superhydrophobic (SHPB) surfaces exhibit a significant reduction in SARS-CoV-2 attachment of up to 99.99995%. We identify the vital importance of solid-liquid adhesion in dominating viral attachment, where the viral activity (N) is proportional to the cube of solid-liquid adhesion (A), N âˆ A3. Our results predict that a surface would be practically free of SARS-CoV-2 deposition when solid-liquid adhesion is ≤1 mN. Engineering surfaces with superhydrophobicity would open an avenue for developing a general approach to preventing fomite formation against the COVID-19 pandemic and future ones.

An epidemic model integrating direct and fomite transmission as well as household structure applied to COVID-19.

This paper stresses its base contribution on a new SIR-type model including direct and fomite transmission as well as the effect of distinct household structures. The model derivation is modulated by several mechanistic processes inherent from typical airborne diseases. The notion of minimum contact radius is included in the direct transmission, facilitating the arguments on physical distancing. As fomite transmission heavily relates to former-trace of sneezes, the vector field of the system naturally contains an integral kernel with time delay indicating the contribution of undetected and non-quarantined asymptomatic cases in accumulating the historical contamination of surfaces. We then increase the complexity by including the different transmission routines within and between households. For airborne diseases, within-household interactions play a significant role in the propagation of the disease rendering countrywide effect. Two steps were taken to include the effect of household structure. The first step subdivides the entire compartments (susceptible, exposed, asymptomatic, symptomatic, recovered, death) into the household level and different infection rates for the direct transmission within and between households were distinguished. Under predefined conditions and assumptions, the governing system on household level can be raised to the community level. The second step then raises the governing system to the country level, where the final state variables estimate the total individuals from all compartments in the country. Two key attributes related to the household structure (number of local households and number of household members) effectively classify countries to be of low or high risk in terms of effective disease propagation. The basic reproductive number is calculated and its biological meaning is invoked properly. The numerical methods for solving the DIDE-system and the parameter estimation problem were mentioned. Our optimal model solutions are in quite good agreement with datasets of COVID-19 active cases and related deaths from Germany and Sri Lanka in early infection, allowing us to hypothesize several unobservable situations in the two countries. Focusing on extending minimum contact radius and reducing the intensity of individual activities, we were able to synthesize the key parameters telling what to practice.

Why is mock care not a good proxy for predicting hand contamination during patient care?

BACKGROUND: Healthcare worker (HCW) behaviours, such as the sequence of their contacts with surfaces and hand hygiene moments, are important for understanding disease transmission. AIM: To propose a method for recording sequences of HCW behaviours during mock vs actual procedures, and to evaluate differences for use in infection risk modelling and staff training. METHODS: Procedures for three types of care were observed under mock and actual settings: intravenous (IV) drip care, observational care and doctors' rounds on a respiratory ward in a university teaching hospital. Contacts and hand hygiene behaviours were recorded in real-time using either a handheld tablet or video cameras. FINDINGS: Actual patient care demonstrated 70% more surface contacts than mock care. It was also 2.4 min longer than mock care, but equal in terms of patient contacts. On average, doctors' rounds took 7.5 min (2.5 min for mock care), whilst auxiliary nurses took 4.9 min for observational care (2.4 min for mock care). Registered nurses took 3.2 min for mock IV care and 3.8 min for actual IV care; this translated into a 44% increase in contacts. In 51% of actual care episodes and 37% of mock care episodes, hand hygiene was performed before patient contact; in comparison, 15% of staff delivering actual care performed hand hygiene after patient contact on leaving the room vs 22% for mock care. The number of overall touches in the patient room was a modest predictor of hand hygiene. Using a model to predict hand contamination from surface contacts for Staphylococcus aureus, Escherichia coli and norovirus, mock care underestimated micro-organisms on hands by approximately 30%.

Interrupting COVID-19 transmission by implementing enhanced traffic control bundling: Implications for global prevention and control efforts.

We argue that enhanced Traffic Control Bundling (eTCB) can interrupt the community-hospital-community transmission cycle, thereby limiting COVID-19's impact. Enhanced TCB is an expansion of the traditional TCB that proved highly effective during Taiwan's 2003 SARS outbreak. TCB's success derived from ensuring that Health Care Workers (HCWs) and patients were protected from fomite, contact and droplet transmission within hospitals. Although TCB proved successful during SARS, achieving a similar level of success with the COVID-19 outbreak requires adapting TCB to the unique manifestations of this new disease. These manifestations include asymptomatic infection, a hyper-affinity to ACE2 receptors resulting in high transmissibility, false negatives, and an incubation period of up to 22 days. Enhanced TCB incorporates the necessary adaptations. In particular, eTCB includes expanding the TCB transition zone to incorporate a new sector - the quarantine ward. This ward houses patients exhibiting atypical manifestations or awaiting definitive diagnosis. A second adaptation involves enhancing the checkpoint hand disinfection and gowning up with Personal Protective Equipment deployed in traditional TCB. Under eTCB, checkpoint hand disinfection and donning of face masks are now required of all visitors who seek to enter hospitals. These enhancements ensure that transmissions by droplets, fomites and contact are disrupted both within hospitals and between hospitals and the broader community. Evidencing eTCB effectiveness is Taiwan's success to date in containing and controlling the community-hospital-community transmission cycle.