Carbon Dioxide Monitoring in Refuse Collection Vehicle Cabins to Reduce the Risk of SARS-CoV-2 Airborne Transmission

During the COVID-19 pandemic, essential workers such as waste collection crews continued to provide services in the UK, but due to their small size, maintaining social distancing inside waste collection vehicle cabins is impossible. Ventilation in cabins of 11 vehicles operating in London was assessed by measuring air supply flow rates and carbon dioxide (CO2) in the driver's cabin, a proxy for exhaled breath. The indoor CO2 indicated that air quality in the cabins was mostly good throughout a working day. However, short episodes of high CO2 levels above 1500 ppm did occur, mainly at the beginning of a shift when driving towards the start of their collection routes. This data indicated that the ventilation systems on the vehicles were primarily recirculating air and the fresh air supply made up only 10-20 % of the total airflow. Following recommendations to partly open windows during shifts and to maintain ventilation systems, a second monitoring campaign was carried out, finding on average, an improvement in ventilation on board the vehicles. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

Assessing the impact of architectural and behavioral interventions for controlling indoor COVID-19 infection risk: An agent-based approach

The COVID-19 pandemic changed our lives, forcing us to reconsider our built environment. In some buildings with high traffic flow, infected individuals release viral particles during movement. The complex interactions between humans, building, and viruses make it difficult to predict indoor infection risk by traditional computational fluid dynamics methods. The paper developed a spatially-explicit agent-based model to simulate indoor respiratory pathogen transmission for buildings with frequent movement of people. The social force model simulating pedestrian movement and a simple forcing method simulating indoor airflow were coupled in an agent-based modeling environment. The impact of architectural and behavioral interventions on the indoor infection risk was then compared by simulating a supermarket case. We found that wearing a mask was the most effective single intervention, with all people wearing masks reducing the percentage of infections to 0.08%. Among the combined interventions, the combination of customer control is the most effective and can reduce the percentage of infections to 0.04%. In addition, the extremely strict combination of all the interventions makes the supermarket free of new infections during its 8-hour operation. The approach can help architects, managers, or the government better understand the effect of nonpharmaceutical interventions to reduce the infection risk and improve the level of indoor safety.

COVID-19: Delphi analysis for the evaluation of the transition from pandemic to endemic in Mexico.

OBJECTIVE: To review and analyze the available information about the COVID-19 pandemic in Mexico and the determining factors for its transition to an endemic phase. MATERIALS AND METHODS: Prospective study based on the Delphi Method with the participation of a panel made up by specialists in infectious diseases, immunology, internal medicine, pulmonology, pediatrics and public health. RESULT(S): 2270 bibliographic sources were identified;after excluding those that offered repetitive information, 454 were included in the final analysis. The main factors that obstruct the transition from a COVID-19 pandemic to an endemic one were defined as the high capacity of SARS-CoV-2 to mutate (since the efficacy of anti-COVID-19 vaccines depends to a large extent on the genetic presentations of the virus) and the high prevalence in the country of comorbidities that make the population more vulnerable against the disease. Strengthening primary care and promoting a culture of surveillance and prevention are essential. CONCLUSION(S): It was concluded, by consensus, that there are factors that obstruct the passage of the COVID-19 pandemic to an endemic phase, including the intrinsic nature of disease control and the unpredictability of virus mutations.Copyright © 2023 Comunicaciones Cientificas Mexicanas S.A. de C.V.. All rights reserved.

Social contact patterns during the COVID-19 pandemic in 21 European countries - evidence from a two-year study.

BACKGROUND: Most countries have enacted some restrictions to reduce social contacts to slow down disease transmission during the COVID-19 pandemic. For nearly two years, individuals likely also adopted new behaviours to avoid pathogen exposure based on personal circumstances. We aimed to understand the way in which different factors affect social contacts - a critical step to improving future pandemic responses. METHODS: The analysis was based on repeated cross-sectional contact survey data collected in a standardized international study from 21 European countries between March 2020 and March 2022. We calculated the mean daily contacts reported using a clustered bootstrap by country and by settings (at home, at work, or in other settings). Where data were available, contact rates during the study period were compared with rates recorded prior to the pandemic. We fitted censored individual-level generalized additive mixed models to examine the effects of various factors on the number of social contacts. RESULTS: The survey recorded 463,336 observations from 96,456 participants. In all countries where comparison data were available, contact rates over the previous two years were substantially lower than those seen prior to the pandemic (approximately from over 10 to < 5), predominantly due to fewer contacts outside the home. Government restrictions imposed immediate effect on contacts, and these effects lingered after the restrictions were lifted. Across countries, the relationships between national policy, individual perceptions, or personal circumstances determining contacts varied. CONCLUSIONS: Our study, coordinated at the regional level, provides important insights into the understanding of the factors associated with social contacts to support future infectious disease outbreak responses.

Perinatal Transmission of SARS-CoV-2 Infection and Its Clinical Attributes: A Single-Center Study From Western Uttar Pradesh.

Background Globally, severe acute respiratory syndrome coronavirus 2 (SARS­CoV­2) has infected millions of people to date. The morbidity and mortality associated with SARS-CoV-2 are higher in diabetics than those with chronic kidney disease and in the elderly. In pregnant women, it causes an increased risk for preeclampsia/eclampsia, infections, intensive care unit (ICU) admission, maternal mortality, and preterm birth. In neonates, SARS­CoV­2 infection has been found to cause stillbirths, growth retardation, premature delivery, increased neonatal intensive care unit (NICU) admission, and need for oxygen support. The neonate can get infected by vertical or horizontal transmission. As most studies have focussed on transmission at the time of birth only, in this study, we explored both vertical and horizontal transmission along with the clinical attributes of those born to mothers with SARS­CoV­2 infection. Methodology A prospective observational study was conducted in the Department of Pediatrics of a tertiary care hospital over 12 months from October 2020 to October 2021. All reverse transcription-polymerase chain reaction (RT-PCR) SARS-CoV-2-positive pregnant females admitted to the facility during the study duration were included. The enrolled mothers were followed till delivery. The mothers and neonates were managed per standard guidelines. Delivery details and neonatal outcomes were recorded. Coronavirus disease 2019 sampling in newborn babies was done at birth (within 24 hours) using a nasopharyngeal swab sample for RTPCR along with cord blood for SARS-CoV-2 immunoglobulin M (IgM). Complete blood count, C-reactive protein, serum electrolytes, random blood sugar, and chest X-ray were obtained for all babies at birth and thereafter according to requirement. In those roomed in with their mother, RT-PCR was repeated at the time of discharge or if they became symptomatic. Results A total of 44 mother-neonate dyads were included in the study. Cord blood IgM for SARS­CoV­2 was negative for all neonates, while throat swab RT-PCR was positive for two (4.5%) neonates immediately after birth. Overall, 13.6% of the neonates were premature, 27.2% of the neonates had low birth weight (<2,500 g), and 6.8% had very low birth weight (<1,500 g). Among those admitted to the NICU, 18.2% had respiratory distress; 4.5% had fever, lethargy, and poor feeding; and hyperbilirubinemia requiring phototherapy was observed in 11.3% of the neonates. Moreover, 4.5% of the neonates had hypocalcemia on initial investigations. Mortality was seen in 2.2% (1/44) of the neonates. Rooming-in and breastfeeding were seen in 68.2% of the neonates. The horizontal transmission was seen in one (3.3%) roomed-in neonate. Conclusions Perinatal transmission of SARS­CoV­2 infection does occur but its rate is not significant. Furthermore, with proper infection prevention and control measures, the risk of perinatal transmission can be decreased. Breastfeeding and rooming-in do not increase infection transmission if the mother takes all precautions.

Novel Corona-Virus Disease 2019 (COVID-19): A Perilous Life-Threatening Epidemic

Background: The widespread of novel coronavirus is a global concern. With each passing day, the novel coronavirus is making its new borders. Research has revealed that the virus produced in bats and was transmitted to humans firstly in Wuhan, Hubei province of China in December 2019. The contagion has been significantly acting as a vulnerable threat to the copious world. Objective(s): The purpose of this review is to provide the valuable and detailed information about the his-torical background, origin, classification, morphology, transmission pattern, symptoms, treatment pa-rameters, number of cases as well as the preventive measures of the corona-virus disease 2019 (COVID-19). Method(s): The disease is transmitted to people by inhalation or close contact of infected droplets. To split the sequential chain of this contagious disease, we need to know about its symptoms, ways of transmission, preventive measures and safety guidelines. Result(s): The widespread of COVID-19 is a global concern. The morbidity rate due to COVID-19 is in-creasing regularly. As for now, there is no specific cure, vaccine and treatment;the lives can be saved only by following the preventive measures and safety guidelines. Conclusion(s): Several clinical trials are in progress for the development of a suitable vaccine to combat this disease. This review shall be helpful in providing detailed information regarding the novel coronavi-rus so that the sequences of such infection can be reduced.Copyright © 2021 Bentham Science Publishers.

Analysis on SARS-CoV-2 contamination in the environment exposure to the SARS-CoV-2 cases in Huangpu District of Shanghai in 2022

Objective To analyze the detection of SARS-CoV-2 in household environment and public place environment of Huangpu District, and describe the feature of SARS-CoV-2 contamination in the environment exposure to the infected cases, so as to support the control strategies such as disinfection and health communication. Methods The results of RT-PCR test for the environmental samples exposure to the cases infected by SARS-CoV-2 during February 1 to March 31 2022 in Huangpu District of Shanghai were collected as the research data. Pearson χ2 was used to test the significance of the differences between positive rates of SARS-CoV-2 contamination. Results From February 1 to March 31, household environment samples had a higher positive rate (6.47%, 234/3 618) of SARS-CoV-2 contamination while the public place samples had a lower one (1.22%, 47/3 582) in Huangpu District of Shanghai (χ2=141.908, P<0.01). Among the household buildings, the lane houses of old style representing poorer living condition had the highest positive rates (8.31%, 96/1 155) of SARS-CoV-2 contamination while the apartments representing better living condition had the lowest (3.59%, 22/612) (F=5.25 P<0.05). Among the samples from household environment, samples regarding sewerage had the highest positive rates (13.30%, 58/436) of SARS-CoV-2 contamination, while samples regarding the tool of cooking and sweeping had the lowest (3.10%, 17/548) (F=9.84 P<0.01). Among the samples from public place environment, samples regarding entertainment tools had the highest positive rates (13.33%, 2/15) of SARS-CoV-2 contamination, while samples regarding the tool of cooking and sweeping had the lowest (0.62%, 4/646) (F=4.22 P<0.01). Conclusion In the environment exposure to the SARS-CoV-2 infected cases, the disinfection, ventilation and cleaning should be intensified strictly. SARS-CoV-2's surviving in sewage environment should be evaluation dynamically. More health communication should be pushed to people of poorer living condition. © 2022 Editorial Office of Chinese Journal of Schistosomiasis Control. All rights reserved.

A Mini Review: Origin, Treatments, Preventions, Real Facts and Viability of the Recent Pandemic of Novel Coronavirus-2019

Background: Outbreak of Coronavirus Disease-2019 (COVID-19) has sent billions of people into lockdown. It has a negative impact on daily life, physical and mental health. Never before was seen such a type of pandemic sparked by a coronavirus. It increased anxiety in the community. Impacts of this disruption affect every sector such as health, finance, education, transport, agriculture, and economical growth of countries. Most of the countries experience insecurity in these sectors. Objective(s): To reduce the spread of the novel Coronavirus-2019 and to bridge the knowledge gap of the research community, frontline health workers as well as those persons who are working in this regard to improve critical health challenges so that the community can plan effective prevention. In the present mini-review, we summarized the origin, route of transmission, current therapies of treatment, preventions, viability and real facts of fatal disease novel Coronavirus-2019 (2019-nCoV). Result(s): Achieving division of a large population into small-small groups and take RT-PCR tests on a very large scale. It will help to identify and isolate an accurate infected person. Isolation of infected cases and quarantine reduce the transmissibility of COVID-19. Conclusion(s): Knowledge about real-time evolution and transmission of the emerging pathogens helps to prevent its infection at all stages. To improve understanding of the risk, mechanism, and treatment in response to COVID-19 is required encouraging case studies, effective treatment therapies, drug discovery and developments. Make awareness in society about sanitation and avoid close contact to escape COVID-19 infection are the best ways of protection.Copyright © 2021 Bentham Science Publishers.

Insights into Molecular Evolution and Increased Transmissibility of SARS-CoV-2

The never-ending race for survival between the virus and its host continues to be a major challenge for biologistsas well as healthcare professionals. Owing to their simple genome organization, capacity for replication, mutation and adaptation - viruses can evolve rapidly, thereby posing a constant threat to human and other animal hosts The animal-human species barrier constitutes a considerable hurdle for zoonotic viruses, and often shields humans from the risk of new outbreaks. However, modern lifestyles and advanced technology have diminished geographic barriers, exposing humans to outbreaks initiated in one part of the world, and amplifying the associated health risks and economic losses across the globe. The novel SARS-CoV-2 outbreak that originated from Wuhan, China at the end of 2019 highlights that humans are continuously living under the threat of emerging zoonotic viruses. The Coronavirus disease 2019 (COVID-19) pandemic continues unabated despite theavailability and deployment of multiple approved vaccines and supportive therapies. Moreover, SARS-CoV-2 variants have emerged which contain mutations that promote viral transmissibility and/or virulence. Furthermore, these new variants have raised concerns over the protective efficacy of current vaccines and the susceptibility of unvaccinated individuals. This chapter discusses the potential causes and factors that influence viral fitness and host selection leading to the emergence of easily transmissible and highly pathogenic SARS-CoV-2 variants. © 2023 by World Scientific Publishing Co. Pte. Ltd.

Analysis of serological surveys of antibodies to SARS-CoV-2 in the United States to estimate parameters needed for transmission modeling and to evaluate and improve the accuracy of predictions.

Seroprevalence studies can estimate proportions of the population that have been infected or vaccinated, including infections that were not reported because of the lack of symptoms or testing. Based on information from studies in the United States from mid-summer 2020 through the end of 2021, we describe proportions of the population with antibodies to SARS-CoV-2 as functions of age and time. Slices through these surfaces at arbitrary times provide initial and target conditions for simulation modeling. They also provide the information needed to calculate age-specific forces of infection, attack rates, and - together with contact rates - age-specific probabilities of infection on contact between susceptible and infectious people. We modified the familiar Susceptible-Exposed-Infectious-Removed (SEIR) model to include features of the biology of COVID-19 that might affect transmission of SARS-CoV-2 and stratified by age and location. We consulted the primary literature or subject matter experts for contact rates and other parameter values. Using time-varying Oxford COVID-19 Government Response Tracker assessments of US state and DC efforts to mitigate the pandemic and compliance with non-pharmaceutical interventions (NPIs) from a YouGov survey fielded in the US during 2020, we estimate that the efficacy of social-distancing when possible and mask-wearing otherwise at reducing susceptibility or infectiousness was 31% during the fall of 2020. Initialized from seroprevalence among people having commercial laboratory tests for purposes other than SARS-CoV-2 infection assessments on 7 September 2020, our age- and location-stratified SEIR population model reproduces seroprevalence among members of the same population on 25 December 2020 quite well. Introducing vaccination mid-December 2020, first of healthcare and other essential workers, followed by older adults, people who were otherwise immunocompromised, and then progressively younger people, our metapopulation model reproduces seroprevalence among blood donors on 4 April 2021 less well, but we believe that the discrepancy is due to vaccinations being under-reported or blood donors being disproportionately vaccinated, if not both. As experimenting with reliable transmission models is the best way to assess the indirect effects of mitigation measures, we determined the impact of vaccination, conditional on NPIs. Results indicate that, during this period, vaccination substantially reduced infections, hospitalizations and deaths. This manuscript was submitted as part of a theme issue on "Modelling COVID-19 and Preparedness for Future Pandemics."

Air curtain as a SARS-CoV-2 spreading mitigation method in a small aircraft cabin

This paper discusses an application of air curtain for reduction of virus-laden droplets transmission from an infected host to other passengers in a small aircraft cabin. The study is restricted to respiratory droplets emitted during coughing. Discrete Particle Method introduced for violent respiratory events (VRE) captured in detail the movement of coughing puff inside the cabin and allowed to study the interaction of droplets with the air curtain's stream and the surrounding air. The results show that the application of the air curtain inhibits the transmission process of small droplets (diameters ranging from 10 to 40 mu m). The air curtain supplied with a limited air mass flow cannot alter the multiphase puff dynamics, but it can be utilized to deflect the virus droplets with lower momentum away from the neighboring passenger. Improved removal efficiency of virus-laden droplets has been achieved owing to the application of the air curtain together with supplementary suction surfaces introduced on the front seat backrest. The virus (SARS-CoV-2) transmission process was also analyzed by means of mass concentration of CO2 exhaled by the infected host, used as a contamination tracker. This part of the work aims at assessment of an applicability of CO2 tracer gas in analysis of virus transmission. Results show that CO2 tracer gas can only be employed for the study of small size droplets dispersion (diameter less or equal to 40 mu m).

[Educating to properly close the toilet knob taps or to replace them]. / Educare a chiudere in modo corretto i rubinetti a manopola del bagno o a sostituirli.

Systematic reviews have shown a prevalence close to 20% of gastrointestinal symptoms in COVID-19 positive patients, with nearly 40% of patients shedding viral RNA in their faeces, even if it may not be infectious, possibly because of inactivation by colonic fluid.According to current evidence, this virus is primarily transmitted by respiratory droplets and contact routes, including contaminated surfaces. The virus is quite stable on stainless steel, being detected up to 48-72 hours after application. Therefore, some individuals can be infected touching common contaminated surfaces, such as bathroom taps. Taps can be underestimated critical points in the transmission chain of the infection. Indeed, just by turning the knob, people leave germs on it, especially after coughing over their hands, sneezing, and/or blowing their nose. After handwashing with soap, user take back their germs when turning the knob. Paradoxically, the following user collects the germs back on his/her fingers by implementing a preventive measure, maybe before putting food into the mouth or wearing contact lenses.The Italian National Institute of Health recommends to clean and disinfect high-touched surfaces, but it is unrealistic and inefficient to do so after each tap use. As an alternative, new toilets should install long elbow-levers - or at least short levers - provided that people are educated to close them with the forearm or the side of the hand. This is already a standard measure in hospitals, but it is particularly important also in high-risk communities, such as retirement homes and prisons. It would be important also in schools, in workplaces, and even in families, contributing to the prevention both of orofaecal and respiratory infections.In the meantime, people should be educated to close existing knobs with disposable paper towel wipes or with toilet paper sheets.

Transmisión del SARS-CoV-2 en escolares durante el primer trimestre del curso 2021/2022 en la provincia de Albacete: incidencia e impacto de las nuevas variantes.

OBJECTIVE: The objective of this study was to know the evolution of the COVID-19 pandemic in the school setting, and the effect of the new variants on it. DESIGN: It is an observational longitudinal descriptive study during the first term of the academic year 21/22. SITE: Community health services. PARTICIPANTS: Preschool, elementary, secondary, and high school students. INTERVENTIONS: none. MAIN MEASUREMENTS: We calculated cumulative incidence stratified by grade, source of infection and follow-up period, percentage of vaccinated cases and correlation between cumulative incidence in schooled children per week and cumulative incidence in the general population. RESULTS: 1526 cases were reported, and the cumulative incidence was 3,17% and 0,48% in within-school acquired cases. 20,9% were vaccinated. During follow-up, there was an important change in incidence from weeks 49/21 on, at the time Omicron began to appear in Spain, with an increase in secondary cases, mostly high school students. We found a high correlation between general population and schooled children's cumulative incidence (R2 = 0,59). CONCLUSIONS: SARS-CoV-2 transmission in school settings has been affected by new circulating variants. Two propagation scenarios were identified, and they were like the community propagation pattern. This supports the hypothesis that school settings reflect the transmission in the community. Reinforcement of preventive measures and surveillance would have a positive effect on school settings.

Current Status of Pandemic COVID-19: A Review

The severe acute respiratory syndrome corona virus 2 (SARS-CoV-2), is spreading worldwide rapidly from its original city of China. Corona virus has the presence of positive sense Ribonucleic acid (RNA) genetic material. The infection causes mild respiratory disease especially in humans across all age groups. The widespread distribution of corona virus in other organisms such as birds, livestock and mammals such as bats, pangolins etc. makes it an important pathogen of concern. It has also been reported the number of people that act as healthy carriers of the virus are approximately 2%, where they do not show any symptoms of the infection but act as a prime source of transmission. Transmission of the virus is usually through large droplets generated during sneezing and coughing and thus can remain viable for several days in favorable atmospheric conditions but can be controlled by the usage of disinfectants. World Health Organization recommends isolation as most efficacious method for the containment of patients that are affected by this virus. At present, there are no particular anti-viral medications or vaccines are correctly present to suppress this infection from spreading. However, Polymerase chain reaction (PCR) methods have proved to be effective for assessing viral RNA but may prove to be very time-consuming assay. Thus, as per the present scenario, more research should be carried out to develop a rapid, user-friendly, diagnostic assay which has high specificity and sensitivity at mass level screening thus enabling the further process of drug designing.

COVID-19 in the Czech Republic 2020 and 2021: comparative analysis of probable work-related transmission of the coronavirus SARS-CoV-2.

OBJECTIVES: The aim of the analysis was to determine the probable places of coronavirus transmission in association with the work and compare the situation between 2020 and 2021. METHODS: The work analysed data from the Information System of Infectious Diseases managed by the Institute of Health Information and Statistics of the Czech Republic in the period from March 2020 - December 2021. RESULTS: 2,483,219 COVID-19 cases were officially confirmed (732,202 during 2020 and 1,338,790 in 2021), from them 140,368 (6%) represented work-related disease, 520,830 cases (21%) work-related contact, and 1,822,021 (73%) out-of-work contact. There were identified 13 occupations with the highest incidence of COVID-19 in the observed period (458,341 cases), in descending order - clerk, machinist, teacher, craftsman, worker/agency worker, driver, sales worker/cashier, warehouse worker/expediter, nurse, manager, food worker, paramedic, and social worker. Comparing 2020 and 2021, there was a difference in the ranking of occupations by incidence of disease. In 2021, the risk of infection acquiring increased for the occupations clerk, machinist, craftsman, worker/agency worker, manager, and food worker, while it decreased for the health professions (nurse, other paramedic, physician) and for social worker; 5,514 cases of COVID-19 were recognized as an occupational disease in 2020 and 2021, from them 5,483 cases (99.4%) in the health and social care economic activity sector. CONCLUSION: The available data show probable exposures to an infectious agent (without proof of specific contact with the source of the infection), of which 27% cases of COVID-19 are related to work (cases of work-related disease and work-related contact represented together the closest relationship to work). Different relevant anti-epidemic measures in the workplace have considerable practical importance for epidemic control. The use of personal protection of the mouth and nose with respirators/muffs is essential to reduce the risk of airborne transmission.

Assessment Model for Rapid Suppression of SARS-CoV-2 Transmission under Government Control.

The rapid suppression of SARS-CoV-2 transmission remains a priority for maintaining public health security throughout the world, and the agile adjustment of government prevention and control strategies according to the spread of the epidemic is crucial for controlling the spread of the epidemic. Thus, in this study, a multi-agent modeling approach was developed for constructing an assessment model for the rapid suppression of SARS-CoV-2 transmission under government control. Different from previous mathematical models, this model combines computer technology and geographic information system to abstract human beings in different states into micro-agents with self-control and independent decision-making ability; defines the rules of agent behavior and interaction; and describes the mobility, heterogeneity, contact behavior patterns, and dynamic interactive feedback mechanism of space environment. The real geospatial and social environment in Taiyuan was considered as a case study. In the implemented model, the government agent could adjust the response level and prevention and control policies for major public health emergencies in real time according to the development of the epidemic, and different intervention strategies were provided to improve disease control methods in the simulation experiment. The simulation results demonstrate that the proposed model is widely applicable, and it can not only judge the effectiveness of intervention measures in time but also analyze the virus transmission status in complex urban systems and its change trend under different intervention measures, thereby providing scientific guidance to support urban public health safety.

Experimental Methods of Investigating Airborne Indoor Virus-Transmissions Adapted to Several Ventilation Measures.

This study introduces a principle that unifies two experimental methods for evaluating airborne indoor virus-transmissions adapted to several ventilation measures. A first-time comparison of mechanical/natural ventilation and air purification with regard to infection risks is enabled. Effortful computational fluid dynamics demand detailed boundary conditions for accurate calculations of indoor airflows, which are often unknown. Hence, a suitable, simple and generalized experimental set up for identifying the spatial and temporal infection risk for different ventilation measures is more qualified even with unknown boundary conditions. A trace gas method is suitable for mechanical and natural ventilation with outdoor air exchange. For an accurate assessment of air purifiers based on filtration, a surrogate particle method is appropriate. The release of a controlled rate of either trace gas or particles simulates an infectious person releasing virus material. Surrounding substance concentration measurements identify the neighborhood exposure. One key aspect of the study is to prove that the requirement of concordant results of both methods is fulfilled. This is the only way to ensure that the comparison of different ventilation measures described above is reliable. Two examples (a two-person office and a classroom) show how practical both methods are and how the principle is applicable for different types and sizes of rooms.

Point-of-care CRISPR/Cas biosensing technology: A promising tool for preventing the possible COVID-19 resurgence caused by contaminated cold-chain food and packaging.

The ongoing coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused great public health concern and has been a global threat due to its high transmissibility and morbidity. Although the SARS-CoV-2 transmission mainly relies on the person-to-person route through the respiratory droplets, the possible transmission through the contaminated cold-chain food and packaging to humans has raised widespread concerns. This review discussed the possibility of SARS-CoV-2 transmission via the contaminated cold-chain food and packaging by tracing the occurrence, the survival of SARS-CoV-2 in the contaminated cold-chain food and packaging, as well as the transmission and outbreaks related to the contaminated cold-chain food and packaging. Rapid, accurate, and reliable diagnostics of SARS-CoV-2 is of great importance for preventing and controlling the COVID-19 resurgence. Therefore, we summarized the recent advances on the emerging clustered regularly interspaced short palindromic repeats (CRISPR)/Cas system-based biosensing technology that is promising and powerful for preventing the possible COVID-19 resurgence caused by the contaminated cold-chain food and packaging during the COVID-19 pandemic, including CRISPR/Cas system-based biosensors and their integration with portable devices (e.g., smartphone, lateral flow assays, microfluidic chips, and nanopores). Impressively, this review not only provided an insight on the possibility of SARS-CoV-2 transmission through the food supply chain, but also proposed the future opportunities and challenges on the development of CRISPR/Cas system-based detection methods for the diagnosis of SARS-CoV-2.

Individual heterogeneity and airborne infection: Effect of non-uniform air distribution

The classical Wells–Riley equation assumes homogeneity of susceptible individuals and environments to airborne exposure. However, individual susceptibility to infection is mostly heterogeneous, and exposure variability could arise from differences in inhalation rate, spatiotemporal non-uniformity of infectious aerosol concentrations, and the exposure trajectory and time. Non-uniform air distribution results in spatial non-uniformity of infectious aerosol concentrations. The non-uniformity effect is essentially a problem of individual infection probability. Here, we derived a general dose-response equation and a heterogeneous Wells–Riley equation accounting for individual variability in infection probability. The heterogeneous Wells-Riley equation shows the potential of the zone air distribution effectiveness to consider spatial non-uniformity under steady-state conditions. An existing quanta generation rate formula was theoretically justified. The new equation was then applied to a restaurant reporting an outbreak of coronavirus disease 2019, with spatial and/or temporal heterogeneity of infectious aerosol concentrations. Our results show the need to include spatial non-uniformity in outbreak investigations. A hypothetical two-zone setup was used to demonstrate how the inter-zonal distribution of clean air and the inter-zonal exchange flow affect airborne infections. An infector in a poorly diluted zone with the greatest number of susceptible individuals would result in the most secondary infections, whereas an infector in a well-ventilated zone with few susceptible individuals would result in the least secondary infections.