Can Air-Conditioning Systems Contribute to the Spread of SARS/MERS/COVID-19 Infection? Insights from a Rapid Review of the Literature

Development of Polymerase Chain Reaction-High-Resolution Melt Assay for Waterborne Pathogens Legionella pneumophila, Vibrio parahaemolyticus, and Camplobacter jejuni

Legionella pneumophila is the waterborne pathogen primarily responsible for causing both Pontiac Fever and Legionnaire's Disease in humans. L. pneumophila is transmitted via aerosolized water droplets. The purpose of this study was to design and test primers to allow for rapid polymerase chain reaction (PCR) melt detection and identification of this infectious agent in cases of clinical or emergency response detection. New PCR primers were designed for this species of bacteria; the primer set was purchased from IDT and the target bacterial DNA was purchased from ATCC. The L. pneumophila primers targeted the macrophage infectivity potentiator gene (mip), which inhibits macrophage phagocytosis. The primers were tested for specificity, repeatability, and sensitivity using PCR-high-resolution melt (HRM) assays. The primer set was found to be specific to the designated bacteria and did not amplify the other twenty-one species from the panel. The L. pneumophila assay was able to be multiplexed. The duplex assay consists of primers for L. pneumophila and Vibrio parahaemolyticus, which are both waterborne pathogens. The triplex assay consists of primers for L. pneumophila, V. parahaemolyticus, and Campylobacter jejuni. The unique melting temperature for the L. pneumophila primer assay is 82.84 ± 0.19 °C, the C. jejuni assay is 78.10 ± 0.58 °C, and the V. parahaemolyticus assay is 86.74 ± 0.65 °C.

Effect of air sterilizers in an outpatient clinic at a tertiary university hospital

Background

After the COVID-19 outbreak, interest in airborne virus infections has increased. We considered ways to reduce the risk of infection to other people by inactivating the virus before it is inhaled into the heating, ventilation, and air conditioning (HVAC) systems. We installed a recently developed air sterilizer in the newly remodeled outpatient clinic of a tertiary university hospital and confirmed its effectiveness.

Methods

After remodeling the ENT outpatient clinic at Chonnam National University Hospital, 15 KOKKOS air sterilizers (Bentech Frontier Co., Ltd., Gwangju, Korea) were installed. Total culturable microorganisms (TCMs) and volatile organic compounds (VOCs) were measured in five separate inspection areas three days before installation, 2 weeks after installation, and 4 weeks after installation.

Results

After measurement of TCMs, improvement in air quality occurred 2 weeks after air sterilizer instatement at all timepoints except inspection area 5, and further improvement was achieved after 4 weeks (p < 0.05). After assessment of VOCs, improvement occurred 4 weeks after air sterilizer connection at all points (p < 0.05).

Conclusion

KOKKOS air sterilizers are effective in improving air quality in an outpatient clinic at a tertiary university hospital.

SARS-CoV-2 infection in meat and poultry workers after the "first wave" (Summer 2020): a cross-sectional study on knowledge, attitudes, practices (KAP) of Italian occupational physicians

BACKGROUND AND AIM

This cross-sectional study assessed knowledge, attitudes and practices (KAP) of Italian Occupational Physicians (OPs) on Coronavirus disease 2019 (COVID-19) among meat/poultry processing plant workers (MPWs) (Summer season 2020).

METHODS

Data were collected through an online questionnaire including demographic characteristics, and items about COVID-19-related KAP in MPWs. A logistic regression was modelled in order to characterize explanatory variables of the outcome variable of having any professional experience as OP in meat/poultry processing industry.

RESULTS

A total of 424 OPs (mean age 49.0 ± 9.1years; 49.5% males) participated into the survey. Despite a generally good level of knowledge on SARS-CoV-2 pandemic, OPs having professional experience with MPWs failed to recognize any increased risk for COVID-19 (Odds Ratio [OR] 0.162; 95% Confidence intervals [95%CI] 0.039-0.670), and were less likely to recommend periodical tests via nasal swabs (OR 0.168, 95%CI 0.047-0.605). On the contrary, they identified socioeconomic status of MPWs as a risk factor (OR 5.686, 95%CI 1.413-22.881), recommending cleaning interventions on changing rooms and canteens (OR 16.090, 95%CI 1.099-259.244).

CONCLUSIONS

In conclusion, we reported a diffuse underestimation of the risk for COVID-19, that was alarmingly higher among professionals who should be more familiar with the specific requirements of MPWs. Some significant knowledge gaps were also clearly identified, stressing the opportunity for tailored educative interventions (www.actabiomedica.it).

Potential airborne human pathogens: A relevant inhabitant in built environments but not considered in indoor air quality standards

Potential airborne human pathogens (PAHPs) may be a relevant component of the air microbiome in built environments. Despite that PAHPs can cause infections, particularly in immunosuppressed patients at medical centers, they are scarcely considered in standards of indoor air quality (IAQ) worldwide. Here, we reviewed the current information on microbial aerosols (bacteria, fungal and viruses) and PAHPs in different types of built environments (e.g., medical center, industrial and non-industrial), including the main factors involved in their dispersion, the methodologies used in their study and their associated biological risks. Our analysis identified the human occupancy and ventilation systems as the primary sources of dispersal of microbial aerosols indoors. We also observed temperature and relative humidity as relevant physicochemical factors regulating the dispersion and viability of some PAHPs. Our analysis revealed that some PAHPs can survive and coexist in different environments while other PAHPs are limited or specific for an environment. In relation to the methodologies (conventional or molecular) the nature of PAHPs and sampling type are pivotal. In this context, indoors air-borne viruses are the less studies because their small size, environmental lability, and absence of efficient sampling techniques and universal molecular markers for their study. Finally, it is noteworthy that PAHPs are not commonly considered and included in IAQ standards worldwide, and when they are included, the total abundance is the single parameter considered and biological risks is excluded. Therefore, we propose a revision, design and establishment of public health policies, regulations and IAQ standards, considering the interactions of diverse factors, such as nature of PAHPs, human occupancy and type of built environments where they develop.

Cleaning technologies integrated in duct flows for the inactivation of pathogenic microorganisms in indoor environments: A critical review of recent innovations and future challenges

Pathogenic microorganisms are a major concern in indoor environments, particularly in sensitive facilities such as hospitals, due to their potential to cause nosocomial infections. This study evaluates the concentration of airborne bacteria and fungi in the University Hospital Complex of Albacete (Spain), comparing the results with recent literature. Staphylococcus is identified as the most prevalent bacterial genus with a percentage distribution of 35%, while Aspergillus represents the dominant fungal genus at 34%. The lack of high Technology Readiness Levels (TRL 6, TRL 7) for effective indoor air purification requires research efforts to bridge this knowledge gap. A screening of disinfection technologies for pathogenic airborne microorganisms such as bacteria and fungi is conducted. The integration of filtration, irradiation or and (electro)chemical gas treatment systems in duct flows is discussed to enhance the design of the air-conditioning systems for indoor air purification. Concerns over microbial growth have led to recent studies on coating commercial fibrous air filters with antimicrobial particles (silver nanoparticles, iron oxide nanowires) and polymeric materials (polyaniline, polyvinylidene fluoride). Promising alternatives to traditional short-wave UV-C energy for disinfection include LED and Far-UVC irradiation systems. Additionally, research explores the use of TiO2 and TiO2 doped with metals (Ag, Cu, Pt) in filters with photocatalytic properties, enabling the utilization of visible or solar light. Hybrid photocatalysis, combining TiO2 with polymers, carbon nanomaterials, or MXene nanomaterials, enhances the photocatalytic process. Chemical treatment systems such as aerosolization of biocidal agents (benzalkonium chloride, hydrogen peroxide, chlorine dioxide or ozone) with their possible combination with other technologies such as adsorption, filtration or photocatalysis, are also tested for gas disinfection. However, the limited number of studies on the use of electrochemical technology poses a challenge for further investigation into gas-phase oxidant generation, without the formation of harmful by-products, to raise its TRL for effectively inactivating airborne microorganisms in indoor environments.

Legionnaires' Disease in Occupational Settings: A Cross-Sectional Study from Northeastern Italy (2019)

In Italy, Legionnaires' Disease (LD) causes >1000 hospital admissions per year, with a lethality rate of 5 to 10%. Occupational exposures could reasonably explain a substantial share of total cases, but the role of Occupational Physicians (OPs) in management and prevention of LD has been scarcely investigated. The present survey therefore evaluates the knowledge, attitudes and practices (KAP) regarding LD from a convenience sample of Italian OPs, focusing on their participation in preventive interventions. A total of 165 OPs were recruited through a training event (Parma, Northeastern Italy, 2019), and completed a specifically designed structured questionnaire. The association between reported participation in preventive interventions and individual factors was analyzed using a binary logistic regression model, calculating corresponding multivariable Odds Ratio (aOR). Overall, participants exhibited satisfactory knowledge of the clinical and diagnostic aspects of LD, while substantial uncertainties were associated epidemiological factors (i.e., notification rate and lethality). Although the majority of participating OPs reportedly assisted at least one hospital (26.7%) and/or a nursing home (42.4%) and/or a wastewater treatment plant, only 41.8% reportedly contributed to the risk assessment for LD and 18.8% promoted specifically designed preventive measures. Working as OPs in nursing homes (aOR 8.732; 95% Confidence Intervals [95%CI] 2.991 to 25.487) and wastewater treatment plants (aOR 8.710; 95%CI 2.844 to 26.668) was associated with participation in the risk assessment for LD, while the promotion of preventive practice was associated with working as an OP in hospitals (aOR 6.792; 95%CI 2.026 to 22.764) and wastewater treatment plants (aOR 4.464, 95%CI 1.363 to 14.619). In other words, the effective participation of the OP in the implementation of preventive measures appears uncommon and is limited to certain occupational settings. Collectively, these results highlight the importance of tailoring specifically designed information campaigns aimed to raise the involvement of OPs in the prevention of LD in occupational settings other than healthcare.

Systematic Review of the Key Factors Influencing the Indoor Airborne Spread of SARS-CoV-2

The COVID-19 pandemic due to the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has been plaguing the world since late 2019/early 2020 and has changed the way we function as a society, halting both economic and social activities worldwide. Classrooms, offices, restaurants, public transport, and other enclosed spaces that typically gather large groups of people indoors, and are considered focal points for the spread of the virus. For society to be able to go "back to normal", it is crucial to keep these places open and functioning. An understanding of the transmission modes occurring in these contexts is essential to set up effective infection control strategies. This understanding was made using a systematic review, according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement (PRISMA) 2020 guidelines. We analyze the different parameters influencing airborne transmission indoors, the mathematical models proposed to understand it, and discuss how we can act on these parameters. Methods to judge infection risks through the analysis of the indoor air quality are described. Various mitigation measures are listed, and their efficiency, feasibility, and acceptability are ranked by a panel of experts in the field. Thus, effective ventilation procedures controlled by CO2-monitoring, continued mask wearing, and a strategic control of room occupancy, among other measures, are put forth to enable a safe return to these essential places.

Dining comfort in elderly care facility dining rooms and influencing factors before and after the outbreak of the COVID-19 pandemic

Introduction

The COVID-19 pandemic has changed dining modes in elderly care facilities. This study explores the relationship between the dining environment of four elderly care facilities and the sensitivity of the elderly residents to it before and after the outbreak of the COVID-19 pandemic.

Methods

The study examined differences in subjective comfort levels by measuring the facilities' physical environment, analysing dining behavior, and surveying the elderly residents. And the study examined how the interaction between the physical environment factors, demographic factors, and dining mode affected the residents' evaluation of their dining comfort.

Results

(1) The physical environmental parameters of the four dining rooms differed between the pre- and post-epidemic periods, as shown by increased Sound Pressure Level (SPL), humidity, and temperature levels. (2) The residents' evaluations of physical environment comfort also changed after the outbreak of the COVID-19 pandemic. The subjective comfort levels of the 'dining with baffle' and 'dining across a seat' modes decreased, though the level of the former was slightly higher than that of the latter. The elderly had stronger SPL tolerance in the dining with baffle mode and dining across a seat mode, and their subjective comfort levels for thermal environment and air quality were higher in the dining across a seat mode. (3) When dining time, crowd density, and communication frequency were kept equal, the subjective comfort level of the elderly in the dining with baffle mode and dining across a seat mode was lower than that in the 'normal' dining mode, when the level in the dining with baffle mode was lower than that in the dining across a seat mode. (4) Differences were observed in subjective comfort levels according to age, education level, and residence duration across the dining modes.

Discussion

The need for changes in dining modes during the COVID-19 isolation period require dining rooms in elderly care facilities to design their physical environments in a way that improves dining comfort for the elderly.

The Impact of Heating, Ventilation, and Air-Conditioning Design Features on the Transmission of Viruses, Including SARS-CoV-2: Overview of Reviews

BACKGROUND

The COVID-19 or SARS-CoV-2 outbreak was declared a pandemic by the World Health Organization in March 2020. Almost 2 years later (early February 2022), the World Health Organization reported over 383 million cases of the disease caused by the virus, with over 5.6 million deaths worldwide. Debate regarding the routes of transmission was substantial early in the pandemic; however, airborne transmission emerged as an important consideration. Infectious airborne agents can spread within the built environment through heating, ventilation, and air-conditioning (HVAC) systems. Multiple features of HVAC systems can influence transmission (eg, ventilation, filtration, UV radiation, and humidity). Understanding how HVAC features influence airborne transmission is critical to mitigate the spread of infectious agents.

OBJECTIVE

Given the airborne transmission of SARS-CoV-2, an overview of reviews was conducted to understand what is already known from the scientific literature about how virus transmission may be affected by HVAC design features in the built environment.

METHODS

Ovid MEDLINE and Compendex were searched from inception to January 2021. Two reviewers independently screened the titles, abstracts, and full text of potentially relevant reviews, using a priori inclusion criteria: systematic reviews examining the effects of HVAC design features on virus transmission. Two reviewers independently assessed the methodological quality using AMSTAR2.

RESULTS

Searching identified 361 citations, of which 45 (12.5%) were potentially relevant and 7 (2%) were included. Reviews were published between 2007 and 2021 and included 47 virus studies. Two earlier reviews (2007 and 2016) of 21 studies found sufficient evidence that mechanical ventilation (airflow patterns and ventilation rates) plays a role in airborne transmission; however, both found insufficient evidence to quantify the minimum mechanical ventilation requirements. One review (2017) of 9 studies examining humidity and indoor air quality found that influenza virus survival was lowest between 40% and 80% relative humidity; the authors noted that ventilation rates were a confounding variable. Two reviews (2021) examined mitigation strategies for coronavirus transmission, finding that transmission decreased with increasing temperature and relative humidity. One review (2020) identified 14 studies examining coronavirus transmission in air-conditioning systems, finding that HVAC systems played a role in virus spread during previous coronavirus outbreaks. One review (2020) examined virus transmission interventions in public ground transportation, finding ventilation and filtration to be effective.

CONCLUSIONS

Seven reviews synthesizing 47 studies demonstrated a role for HVAC in mitigating airborne virus transmission. Ventilation, humidity, temperature, and filtration can play a role in the viability and transmission of viruses, including coronaviruses. Recommendations for minimum standards were not possible owing to few studies investigating a given HVAC parameter. This overview examining HVAC design features and their effects on the airborne transmission of viruses serves as a starting point for future systematic reviews and identifying priorities for primary research.

Cumulative effects of air pollution and climate drivers on COVID-19 multiwaves in Bucharest, Romania

Over more than two years of global health crisis due to ongoing COVID-19 pandemic, Romania experienced a five-wave pattern. This study aims to assess the potential impact of environmental drivers on COVID-19 transmission in Bucharest, capital of Romania during the analyzed epidemic period. Through descriptive statistics and cross-correlation tests applied to time series of daily observational and geospatial data of major outdoor inhalable particulate matter with aerodynamic diameter ≤ 2.5 µm (PM2.5) or ≤ 10 µm (PM10), nitrogen dioxide (NO2), ozone (O3), sulfur dioxide (SO2), carbon monoxide (CO), Aerosol Optical Depth at 550 nm (AOD) and radon (222Rn), we investigated the COVID-19 waves patterns under different meteorological conditions. This study examined the contribution of individual climate variables on the ground level air pollutants concentrations and COVID-19 disease severity. As compared to the long-term average AOD over Bucharest from 2015 to 2019, for the same year periods, this study revealed major AOD level reduction by ~28 % during the spring lockdown of the first COVID-19 wave (15 March 2020-15 May 2020), and ~16 % during the third COVID-19 wave (1 February 2021-1 June 2021). This study found positive correlations between exposure to air pollutants PM2.5, PM10, NO2, SO2, CO and 222Rn, and significant negative correlations, especially for spring-summer periods between ground O3 levels, air temperature, Planetary Boundary Layer height, and surface solar irradiance with COVID-19 incidence and deaths. For the analyzed time period 1 January 2020-1 April 2022, before and during each COVID-19 wave were recorded stagnant synoptic anticyclonic conditions favorable for SARS-CoV-2 virus spreading, with positive Omega surface charts composite average (Pa/s) at 850 mb during fall- winter seasons, clearly evidenced for the second, the fourth and the fifth waves. These findings are relevant for viral infections controls and health safety strategies design in highly polluted urban environments.

Impacts of exposure to air pollution, radon and climate drivers on the COVID-19 pandemic in Bucharest, Romania: A time series study

During the ongoing global COVID-19 pandemic disease, like several countries, Romania experienced a multiwaves pattern over more than two years. The spreading pattern of SARS-CoV-2 pathogens in the Bucharest, capital of Romania is a multi-factorial process involving among other factors outdoor environmental variables and viral inactivation. Through descriptive statistics and cross-correlation analysis applied to daily time series of observational and geospatial data, this study aims to evaluate the synergy of COVID-19 incidence and lethality with air pollution and radon under different climate conditions, which may exacerbate the coronavirus' effect on human health. During the entire analyzed period 1 January 2020-21 December 2021, for each of the four COVID-19 waves were recorded different anomalous anticyclonic synoptic meteorological patterns in the mid-troposphere, and favorable stability conditions during fall-early winter seasons for COVID-19 disease fast-spreading, mostly during the second, and the fourth waves. As the temporal pattern of airborne SARS-CoV-2 and its mutagen variants is affected by seasonal variability of the main air pollutants and climate parameters, this paper found: 1) the daily outdoor exposures to air pollutants (particulate matter PM2.5 and PM10, nitrogen dioxide-NO₂, sulfur dioxide-SO₂, carbon monoxide-CO) and radon - ²²²Rn, are directly correlated with the daily COVID-19 incidence and mortality, and may contribute to the spread and the severity of the pandemic; 2) the daily ground ozone-O₃ levels, air temperature, Planetary Boundary Layer height, and surface solar irradiance are anticorrelated with the daily new COVID-19 incidence and deaths, averageingful for spring-summer periods. Outdoor exposure to ambient air pollution associated with radon is a non-negligible driver of COVID-19 transmission in large metropolitan areas, and climate variables are risk factors in spreading the viral infection. The findings of this study provide useful information for public health authorities and decision-makers to develop future pandemic diseases strategies in high polluted metropolitan environments.

Prediction of respiratory droplets evolution for safer academic facilities planning amid COVID-19 and future pandemics: A numerical approach

Airborne dispersion of the novel SARS-CoV-2 through the droplets produced during expiratory activities is one of the main transmission mechanisms of this virus from one person to another. Understanding how these droplets spread when infected humans with COVID-19 or other airborne infectious diseases breathe, cough or sneeze is essential for improving prevention strategies in academic facilities. This work aims to assess the transport and fate of droplets in indoor environments using Computational Fluid Dynamics (CFD). This study employs unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations with the Euler-Lagrange approach to visualize the location of thousands of droplets released in a respiratory event and their size evolution. Furthermore, we assess the dispersion of coughing, sneezing, and breathing saliva droplets from an infected source in a classroom with air conditioning and multiple occupants. The results indicate that the suggested social distancing protocol is not enough to avoid the transmission of COVID-19 since small saliva droplets ( ≤ 12 μm) can travel in the streamwise direction up to 4 m when an infected person coughs and more than 7 m when sneezes. These droplets can reach those distances even when there is no airflow from the wind or ventilation systems. The number of airborne droplets in locations close to the respiratory system of a healthy person increases when the relative humidity of the indoor environment is low. This work sets an accurate, rapid, and validated numerical framework reproducible for various indoor environments integrating qualitative and quantitative data analysis of the droplet size evolution of respiratory events for a safer design of physical distancing standards and air cleaning technologies.

Ventilation strategies to reduce airborne transmission of viruses in classrooms: A systematic review of scientific literature

The recent pandemic due to SARS-CoV-2 has brought to light the need for strategies to mitigate contagion between human beings. Apart from hygiene measures and social distancing, air ventilation highly prevents airborne transmission within enclosed spaces. Among others, educational environments become critical in strategic planning to control the spread of pathogens and viruses amongst the population, mainly in cold conditions. In the event of a virus outbreak - such as COVID or influenza - many school classrooms still lack the means to guarantee secure and healthy environments. The present review examines school contexts that implement air ventilation strategies to reduce the risk of contagion between students. The analysed articles present past experiences that use either natural or mechanical systems assessed through mathematical models, numerical models, or full-scale experiments. For naturally ventilated classrooms, the studies highlight the importance of the architectural design of educational spaces and propose strategies for aeration control such as CO₂-based control and risk-infection control. When it comes to implementing mechanical ventilation in classrooms, different systems with different airflow patterns are assessed based on their ability to remove airborne pathogens considering parameters like the age of air and the generation of airflow streamlines. Moreover, studies report that programmed mechanical ventilation systems can reduce risk-infection during pandemic events. In addition to providing a systematic picture of scientific studies in the field, the findings of this review can be a valuable reference for school administrators and policymakers to implement the best strategies in their classroom settings towards reducing infection risks.

Risk of Surgeon Contracting COVID-19 while Operating on COVID-19-Positive Patient, Impact of Safety Measures: Lessons Learnt

Introduction On March 11, 2020, the novel coronavirus disease 2019 (COVID-19) was declared as a pandemic. General surgeons provide care to COVID-19 positive patients requiring emergency surgeries and hence are exposed to the virus. Surgery on COVID-19-positive patient itself is a major risk factor for surgeon to contract COVID-19 infection. Noticeably, there is no data regarding number of surgeons who have contracted COVID-19 after operating on COVID-19-positive patients. Hence, the aim of this study was to find out the exact incidence of COVID-19 among surgeons operating on COVID-19-positive patients and to analyze the impact of safety measures practiced by us.

Methodology The study was conducted in a tertiary care center in Mumbai. It was a retrospective observational study with duration of 5 months from May 1, 2020, to September 30, 2020. Only those surgeons (faculty and resident doctors) were included who performed surgeries on COVID-19-positive patients (diagnosed by reverse-transcription polymerase chain reaction [RT-PCR] test) and gave consent for participation. As an institutional protocol, all patients undergoing surgery were tested by RT-PCR test (irrespective of chest X-ray or symptoms). Nasopharyngeal swabs for COVID-19 disease were collected prior to procedure but in some of these, results came after surgery. Still such patients were included in this study. Irrespective of COVID-19 status, same precautions were taken for all surgeries. The details of the patients like date of surgery, age, sex, surgery performed, duration of surgery, type of anesthesia used, and operating surgeon were noted from operation room (OR) register. Details of surgeons (faculty and resident doctors) who fulfilled inclusion criteria were noted by interview in terms of their demographic parameters, such as age, sex, designation, experience in years after completing postgraduation, comorbidities, whether they ever contracted COVID-19 (if yes, date), and safety measures practiced (yes, no, or cannot recollect). Patient was assumed to be the source only if the surgeon contracted COVID-19 within 14 days of surgery.

Results A total of 34 surgeons (7 faculty and 27 residents) conducted 41 surgeries on COVID-19-positive patients during the study period. All of them gave consent for participation in the study. More than one surgeon was involved in a particular surgery. Hence, there were 78 occasions (faculty during 16 occasions and resident doctors on 62 occasions) when surgeons were at risk to contract COVID-19 while operating on patients (n = 78). These surgeries had similar/comparable risk of COVID-19 exposure to surgeons and procedures with excessive exposure risk like airway procedures did not happen during the study period. The mean age of surgeon was 27.92 years (n = 78, standard deviation = 5.71) and median experience of faculty after completion of postgraduate degree was 7 years (n = 16, interquartile range [IQR] = 1.25–11.0). Only one faculty had comorbidity (diabetes mellitus). Duration of surgeries ranged from 50 to 420 minutes with median being 190 minutes (n = 41, IQR = 120–240). Only one surgeon (male faculty) contracted COVID-19 within 14 days of surgery (1.3% incidence, n = 78), a total of seven surgeons contracted COVID-19 during study period but not within 14 days of surgery (source other than patient operated) and all remaining surgeons were asymptomatic throughout the study period. The surgeon who contracted COVID-19 (within 14 days) performed surgery for 260 minutes and under general anesthesia. All the surgeons followed standard steps of donning and doffing, used personal protective equipment (PPE) body cover, shoe cover, hood, double pair of gloves, and N-95 masks at all times (n = 78). Intubation box was used in 100% cases of general anesthesia (n = 19). Fogging of OR after each surgery and interval of 20 minutes between surgeries was followed in 100% cases. Also, patient was wearing mask at all possible times and anesthetist and support staff used PPE during all surgeries. Hence the relationship between COVID-19 status and these safety measures cannot be assessed. Goggles and face shields were not used on 88.5% (n = 78) and 93.2% (n = 73, because five surgeons could not recollect whether they used face shields or not) occasions, respectively. Also, immediate shower after surgery was not taken on 93.6% occasions (n = 78). The surgeon who contracted COVID-19 had neither used goggles nor face shield. Also, he did not take shower immediately after surgery. However, there was no significant association between use of goggles, face shields, or shower after surgery and contraction of COVID-19 after operating patients (Fisher's exact p = 1.000). Air conditioner was switched-off only in 7.3% surgeries (n = 41). Smoke evacuator (cautery with attached suction) was not used in 97.6% cases. Clinical documentation (handling of patient's files) was done outside OR in only 17.1% surgeries (n = 41). However, there was no significant association between these safety measures and contraction of COVID-19 (Fisher's exact p = 1.000). General anesthesia was used in 19 surgeries (46.3%) while spinal anesthesia in 16 surgeries (39%), local anesthesia in 5 surgeries (12.2%), and total intravenous anesthesia (TIVA) in one surgery (2.4%). However, there was no significant association between type of anesthesia given during surgery and contraction of COVID-19 after operating on patients with Fisher's exact p-value of 1.000.

Conclusion Even though safety measures, like goggles, face shield, switching-off of air conditioner, use of smoke evacuator, and shower, immediately after surgery were not practiced in majority of cases, surgeon positivity rate was significantly less. Also, there was no use of negative pressure in OR. Hence, their significance becomes questionable. Although adopting all universal safety measures is in everyone's best interest, it is seldom cost-effective. To reduce resource exhaustion, especially in a pandemic situation, the use of various safety measures and staff must be balanced. Use and promotion of unnecessary safety measures leads to added health care costs and fear among health care workers in case of unavailability. Even though our study has a small sample size and has its own limitations, it can guide future studies to strengthen recommendations and reduce health care costs. This will also help in future epidemics/pandemics.

Ventilation strategies and design impacts on indoor airborne transmission: A review

The COVID-19 outbreak has brought the indoor airborne transmission issue to the forefront. Although ventilation systems provide clean air and dilute indoor contaminated air, there is strong evidence that airborne transmission is the main route for contamination spread. This review paper aims to critically investigate ventilation impacts on particle spread and identify efficient ventilation strategies in controlling aerosol distribution in clinical and non-clinical environments. This article also examines influential ventilation design features (i.e., exhaust location) affecting ventilation performance in preventing aerosols spread. This paper shortlisted published documents for a review based on identification (keywords), pre-processing, screening, and eligibility of these articles. The literature review emphasizes the importance of ventilation systems' design and demonstrates all strategies (i.e., mechanical ventilation) could efficiently remove particles if appropriately designed. The study highlights the need for occupant-based ventilation systems, such as personalized ventilation instead of central systems, to reduce cross-infections. The literature underlines critical impacts of design features like ventilation rates and the number and location of exhausts and suggests designing systems considering airborne transmission. This review underpins that a higher ventilation rate should not be regarded as a sole indicator for designing ventilation systems because it cannot guarantee reducing risks. Using filtration and decontamination devices based on building functionalities and particle sizes can also increase ventilation performance. This paper suggests future research on optimizing ventilation systems, particularly in high infection risk spaces such as multi-storey hotel quarantine facilities. This review contributes to adjusting ventilation facilities to control indoor aerosol transmission.

Impact of improved indoor environment on recovery from COVID-19 infections: a review of literature

Purpose

This study aims to explore the impact of the indoor environment on recovery from COVID-19 infections. Extant literature on the impact of the four key themes of the indoor environment (indoor air quality, indoor thermal quality, daylighting and visual comfort, and acoustic comfort) on COVID-19 infection and recovery rates were reviewed.

Design/methodology/approach

Data collection for this study was based on extant literature within the Scopus database and scoped to a time frame of 2020–2021 because the topical issue of indoor environmental quality (IEQ) and its impact on COVID-19 arose in the wake of the pandemic. In total, 224 documents were systematically desk reviewed from various journals.

Findings

The study identified that air pollutants such as PM2.5 and PM10 as well as air-conditioned places, low ambient temperatures, poor ventilation and no views of the outdoor environment were deteriorating factors for COVID-19 patients. On the other hand, proper ventilation, the use of air cleaners, views of the outdoor environment and allowance for ample daylighting were improvement factors for COVID-19 patients. The inter-relationship of the various concepts was presented in an ontology chart.

Practical implications

As COVID-19 still exists and keeps evolving, this study provides suggestions to industry professionals, especially health-care Facility Managers, to create a post-pandemic environment focusing on the IEQ and finding long-term and reliable solutions for the well-being of occupants. Adaptability is crucial. New, creative technology solutions are being introduced daily, but it is up to the facility managers and health-care professionals to analyse and specify the most cost- and outcome-effective technologies for their facility.

Originality/value

The study brought to light the pivotal role of the indoor environment on the health and well-being of occupants, particularly in the contraction, spread, prevention and control of infectious diseases such as COVID-19.

Passively sensing SARS-CoV-2 RNA in public transit buses

Affordably tracking the transmission of respiratory infectious diseases in urban transport infrastructures can inform individuals about potential exposure to diseases and guide public policymakers to prepare timely responses based on geographical transmission in different areas in the city. Towards that end, we designed and tested a method to detect SARS-CoV-2 RNA in the air filters of public buses, revealing that air filters could be used as passive fabric sensors for the detection of viral presence. We placed and retrieved filters in the existing HVAC systems of public buses to test for the presence of trapped SARS-CoV-2 RNA using phenol-chloroform extraction and RT-qPCR. SARS-CoV-2 RNA was detected in 14% (5/37) of public bus filters tested in Seattle, Washington, from August 2020 to March 2021. These results indicate that this sensing system is feasible and that, if scaled, this method could provide a unique lens into the geographically relevant transmission of SARS-CoV-2 through public transit rider vectors, pooling samples of riders over time in a passive manner without installing any additional systems on transit vehicles.

A spatiotemporally resolved infection risk model for airborne transmission of COVID-19 variants in indoor spaces

The classic Wells-Riley model is widely used for estimation of the transmission risk of airborne pathogens in indoor spaces. However, the predictive capability of this zero-dimensional model is limited as it does not resolve the highly heterogeneous spatiotemporal distribution of airborne pathogens, and the infection risk is poorly quantified for many pathogens. In this study we address these shortcomings by developing a novel spatiotemporally resolved Wells-Riley model for prediction of the transmission risk of different COVID-19 variants in indoor environments. This modelling framework properly accounts for airborne infection risk by incorporating the latest clinical data regarding viral shedding by COVID-19 patients and SARS-CoV-2 infecting human cells. The spatiotemporal distribution of airborne pathogens is determined via computational fluid dynamics (CFD) simulations of airflow and aerosol transport, leading to an integrated model of infection risk associated with the exposure to SARS-CoV-2, which can produce quantitative 3D infection risk map for a specific SARS-CoV-2 variant in a given indoor space. Application of this model to airborne COVID-19 transmission within a hospital ward demonstrates the impact of different virus variants and respiratory PPE upon transmission risk. With the emergence of highly contagious SARS-CoV-2 variants such as the Delta and Omicron strains, respiratory PPE alone may not provide effective protection. These findings suggest a combination of optimal ventilation and respiratory PPE must be developed to effectively control the transmission of COVID-19 in healthcare settings and indoor spaces in general. This generalised risk estimation framework has the flexibility to incorporate further clinical data as such becomes available, and can be readily applied to consider a wide range of factors that impact transmission risk, including location and movement of infectious persons, virus variant and stage of infection, level of PPE and vaccination of infectious and susceptible individuals, impacts of coughing, sneezing, talking and breathing, and natural and mechanised ventilation and filtration.

Identifying higher risk subgroups of health care workers for priority vaccination against COVID-19

Background:

Health care workers (HCWs) are exposed to high risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection due to close contact with infected patients in hospital. The objective of this study was to estimate the seroprevalence and to identify the exposure risk of various subgroups among HCWs to prioritize them for early vaccination.

Methods:

This was a multicentre cross-sectional study conducted between 15 and 29 June 2020. A total of 987 HCWs were recruited randomly from two major tertiary-care hospitals of Peshawar city, Pakistan. The HCWs included doctors, nurses, paramedics and hospital support staff. The US Food and Drug Administration (FDA)–approved kit was used for the detection of SARS-CoV-2 antibodies.

Results:

Overall, 310 (31.4%) HCWs were seropositive for SARS-CoV-2 antibodies (95% confidence interval, CI: 28.5–34.4). Seroprevalence was higher in males (33.5%) and in age group 51–60 years (40.9%). Seropositivity increased with increasing age from 8.3% in age group ⩽20 to 40.9% in 51–60 years of age group (p < 0.05). The highest seroprevalence was identified in paramedical staff (42·5%, 95% CI: 36.6–48.6) followed by nursing staff (38·8%, 95% CI: 32.1–45.7). In logistic regression, being a male HCW led to higher risk of seropositivity (odds ratio, OR: 1.50, 95% CI: 1·06–2.13. p < 0.05) compared with female staff members. The odds of seropositivity was higher in nurses (OR: 3·47, 95% CI: 1.99–6.05. p < 0.01), paramedical staff (OR: 3·19, 95% CI: 1.93–5.28. p < 0.01) and hospital support staff (OR: 2·47, 95% CI: 1.29–4.7. p < 0.01) compared with consultants.

Conclusion:

Overall, our results concluded that nursing and paramedical staff are at higher risk and should be vaccinated on priority.

Occupations and Sickness-Related Absences during the COVID-19 Pandemic

Pandemic frontline occupations consist of disproportionately low socioeconomic status and racial minority workers. Documenting occupational health disparities is therefore crucial for understanding COVID-19-related health inequalities in the United States. This study uses Current Population Survey microdata to estimate occupational differences in sickness-related absences (SAs) from work in March through June 2020 and their contribution to educational, racial-ethnic, and nativity health disparities. We find that there has been an unprecedented rise in SAs concentrated in transportation, food-related, and personal care and service occupations. SA rates were 6 times higher in these occupations than in non-health-care professions. The greatest increases were in occupations that are unsuitable for remote work, require workers to work close to others, pay low wages, and rarely provide health insurance. Workers in these occupations are disproportionately Black, Hispanic, indigenous, and immigrants. Occupation contributes 41% of the total of Black/white differences and 54% of educational differences in SAs.

Occupations and Sickness-Related Absences during the COVID-19 Pandemic

Pandemic frontline occupations consist of disproportionately low socioeconomic status and racial minority workers. Documenting occupational health disparities is therefore crucial for understanding COVID-19-related health inequalities in the United States. This study uses Current Population Survey microdata to estimate occupational differences in sickness-related absences (SAs) from work in March through June 2020 and their contribution to educational, racial-ethnic, and nativity health disparities. We find that there has been an unprecedented rise in SAs concentrated in transportation, food-related, and personal care and service occupations. SA rates were 6 times higher in these occupations than in non-health-care professions. The greatest increases were in occupations that are unsuitable for remote work, require workers to work close to others, pay low wages, and rarely provide health insurance. Workers in these occupations are disproportionately Black, Hispanic, indigenous, and immigrants. Occupation contributes 41% of the total of Black/white differences and 54% of educational differences in SAs.

Simulation Studies Provide Evidence of Aerosol Transmission of SARS-CoV-2 in a Multi-Story Building via Air Supply, Exhaust and Sanitary Pipelines

A cross-layer non-vertical transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) occurred in a quarantine hotel in Guangzhou, Guangdong Province, China in June 2021. To explore the cross-layer transmission path and influencing factors of viral aerosol, we set up different scenarios to carry out simulation experiments. The results showed that the air in the polluted room can enter the corridor by opening the door to take food and move out the garbage, then mix with the fresh air taken from the outside as part of the air supply of the central air conditioning system and re-enter into different rooms on the same floor leading to the same-layer transmission. In addition, flushing the toilet after defecation and urination will produce viral aerosol that pollutes rooms on different floors through the exhaust system and the vertical drainage pipe in the bathroom, resulting in cross-layer vertical transmission, also aggravating the transmission in different rooms on the same floor after mixing with the air of the room and entering the corridor to become part of the air supply, and meanwhile, continuing to increase the cross-layer transmission through the vertical drainage pipe. Therefore, the air conditioning and ventilation system of the quarantine hotel should be operated in full fresh air mode and close the return air; the exhaust volume of the bathroom should be greater than the fresh air volume. The exhaust pipe of the bathroom should be independently set and cannot be interconnected or connected in series. The riser of the sewage and drainage pipeline of the bathroom should maintain vertical to exhaust independently and cannot be arbitrarily changed to horizontal pipe assembly.

Environmental surface contamination with SARS-CoV-2 in professional football clubs

Background: We assessed SARS-CoV-2 contamination of random surfaces in football training facilities in an environment with a high prevalence of infections.Methods: In six clubs of the Qatar Stars League, surfaces of random locations (high-touch areas, ventilation systems, toilets, cleaning tools, freezers, pantries) in routinely cleaned training facilities, locker rooms, medical and administrative areas were swabbed for SARS-CoV-2. The swabs were screened for the presence of viral RNA using a SARS-CoV-2 qPCR Probe Assay.Results: None of the 103 swabs reached a cycle threshold (cT) value ≤30 (strong viral presence, suggestive of potential surface transmission). Four samples showed cT values >30 and <35 (low quantity of virus) and 16 swabs returned a cT value ≥35 and <40 (inactive virus remnants). The remaining 83 samples were negative (cT value ≥40). Most samples with viral or viral remnant presence originated from high-touch areas.Conclusion: We did not find evidence for potential surface transmission in football club facilities when routine cleaning procedures are in place despite the presence of infected subjects.

Research and Development of a COVID-19 Tracking System in Order to Implement Analytical Tools to Reduce the Infection Risk

The whole world is currently focused on COVID-19, which causes considerable economic and social damage. The disease is spreading rapidly through the population, and the effort to stop the spread is entirely still failing. In our article, we want to contribute to the improvement of the situation. We propose a tracking system that would identify affected people with greater accuracy than medical staff can. The main goal was to design hardware and construct a device that would track anonymous risky contacts in areas with a highly concentrated population, such as schools, hospitals, large social events, and companies. We have chosen a 2.4 GHz proprietary protocol for contact monitoring and mutual communication of individual devices. The 2.4 GHz proprietary protocol has many advantages such as a low price and higher resistance to interference and thus offers benefits. We conducted a pilot experiment to catch bugs in the system. The device is in the form of a bracelet and captures signals from other bracelets worn at a particular location. In case of contact with an infected person, the alarm is activated. This article describes the concept of the tracking system, the design of the devices, initial tests, and plans for future use.

A review of methods to reduce the probability of the airborne spread of COVID-19 in ventilation systems and enclosed spaces

COVID-19 forced the human population to rethink its way of living. The threat posed by the potential spread of the virus via an airborne transmission mode through ventilation systems in buildings and enclosed spaces has been recognized as a major concern. To mitigate this threat, researchers have explored different technologies and methods that can remove or decrease the concentration of the virus in ventilation systems and enclosed spaces. Although many technologies and methods have already been researched, some are currently available on the market, but their effectiveness and safety concerns have not been fully investigated. To acquire a broader view and collective perspective of the current research and development status, this paper discusses a comprehensive review of various workable technologies and methods to combat airborne viruses, e.g., COVID-19, in ventilation systems and enclosed spaces. These technologies and methods include an increase in ventilation, high-efficiency air filtration, ionization of the air, environmental condition control, ultraviolet germicidal irradiation, non-thermal plasma and reactive oxygen species, filter coatings, chemical disinfectants, and heat inactivation. Research gaps have been identified and discussed, and recommendations for applying such technologies and methods have also been provided in this article.

Aerodynamic analysis of hospital ventilation according to seasonal variations. A simulation approach to prevent airborne viral transmission pathway during Covid-19 pandemic

During the Covid-19 pandemic, location of the SARS-CoV-2 infected patients inside the hospital is a major issue to prevent viral cross-transmission. The objective of this study was to evaluate the risk of contamination through aerosol by using a global approach of the multiple environmental parameters to simulate, including seasonal context. A computational fluid dynamic (CFD) simulation based on the Lattice Boltzmann Method approach was used to predict airflow on the entire floor of a private hospital in Paris. The risk of contamination outside the rooms was evaluated by using a water vapor mass fraction tracker. Finally, the air contamination was estimated by a "cough model" producing several punctual emissions of contaminated air from potentially infected patients. In a winter configuration, the simulation showed a well-balanced ventilation on the floor and especially inside the rooms. After cough emissions from COVID-positive rooms, no significant contamination was observed in the circulation area, public waiting space and nurse office. On the contrary, in a summer configuration, the temperature difference due to the impact of the sun radiation between both sides of the building created additional air transport increasing the contamination risk in neighboring rooms and public spaces. Airborne spread was limited to rooms during winter conditions. On the contrary, during summer conditions, market airflow with potentially contaminated air coming from rooms located on the side of the building exposed to solar radiation was evidenced. These observations have implications to locate infected patients inside the building and for the conception of future health care structures.

A systematic review and meta-analysis of indoor bioaerosols in hospitals: The influence of heating, ventilation, and air conditioning

OBJECTIVES

To evaluate (1) the relationship between heating, ventilation, and air conditioning (HVAC) systems and bioaerosol concentrations in hospital rooms, and (2) the effectiveness of laminar air flow (LAF) and high efficiency particulate air (HEPA) according to the indoor bioaerosol concentrations.

METHODS

Databases of Embase, PubMed, Cochrane Library, MEDLINE, and Web of Science were searched from 1st January 2000 to 31st December 2020. Two reviewers independently extracted data and assessed the quality of the studies. The samples obtained from different areas of hospitals were grouped and described statistically. Furthermore, the meta-analysis of LAF and HEPA were performed using random-effects models. The methodological quality of the studies included in the meta-analysis was assessed using the checklist recommended by the Agency for Healthcare Research and Quality.

RESULTS

The mean CFU/m3 of the conventional HVAC rooms and enhanced HVAC rooms was lower than that of rooms without HVAC systems. Furthermore, the use of the HEPA filter reduced bacteria by 113.13 (95% CI: -197.89, -28.38) CFU/m3 and fungi by 6.53 (95% CI: -10.50, -2.55) CFU/m3. Meanwhile, the indoor bacterial concentration of LAF systems decreased by 40.05 (95% CI: -55.52, -24.58) CFU/m3 compared to that of conventional HVAC systems.

CONCLUSIONS

The HVAC systems in hospitals can effectively remove bioaerosols. Further, the use of HEPA filters is an effective option for areas that are under-ventilated and require additional protection. However, other components of the LAF system other than the HEPA filter are not conducive to removing airborne bacteria and fungi.

LIMITATION OF STUDY

Although our study analysed the overall trend of indoor bioaerosols, the conclusions cannot be extrapolated to rare, hard-to-culture, and highly pathogenic species, as well as species complexes. These species require specific culture conditions or different sampling requirements. Investigating the effects of HVAC systems on these species via conventional culture counting methods is challenging and further analysis that includes combining molecular identification methods is necessary.

STRENGTH OF THE STUDY

Our study was the first meta-analysis to evaluate the effect of HVAC systems on indoor bioaerosols through microbial incubation count. Our study demonstrated that HVAC systems could effectively reduce overall bioaerosol concentrations to maintain better indoor air quality. Moreover, our study provided further evidence that other components of the LAF system other than the HEPA filter are not conducive to removing airborne bacteria and fungi.

PRACTICAL IMPLICATION

Our research showed that HEPA filters are more effective at removing bioaerosols in HVAC systems than the current LAF system. Therefore, instead of opting for the more costly LAF system, a filter with a higher filtration rate would be a better choice for indoor environments that require higher air quality; this is valuable for operating room construction and maintenance budget allocation.

Evaluating heating, ventilation, and air-conditioning systems toward minimizing the airborne transmission risk of Mucormycosis and COVID-19 infections in built environment

This ongoing global pandemic of the COVID-19 has generated a significant international concern for our respiratory health. For instance, the breakout of the COVID-19 pandemic was directly linked to the spread of infectious particles in indoor environments between humans, underlining the significance of rigorous and effective actions to limit the transmission of diseases. Recently, Mucormycosis infections in COVID-19 patients have been identified. This investigation aims to investigate potential infection control HVAC solutions for indoor environments, as well as their core mechanisms for reducing infectious disease risk through simulation models of a valid building in a hot climatic region. Considering recent international recommendations, the investigation relies on a methodology of testing a validated building energy model to several systems in the light of infectious diseases prevention. All proposed models are exposed to cost analysis in line with carbon emissions, and indoor thermal conditions. The analysis outlined through parametric simulations, the effectiveness of the proposed DOAS in supplying 100% fresh ventilation air and enhancing the control of the indoor relative humidity simultaneously. Finally, through an enviro-economic assessment, the study concluded that the DOAS model reduced the CO₂ emissions to 691 tons, with a potential of reducing HVAC and whole-building energy use by 37% and 16%, respectively in the hot arid climate, with a return on investment of about 6%.

A Community-Based Management of COVID-19 in a Mobile Container Unit

Vaccine uptake is a multifactor measure of successful immunization outcomes that includes access to healthcare and vaccine hesitancy for both healthcare workers and communities. The present coronavirus disease (COVID-19) pandemic has highlighted the need for novel strategies to expand vaccine coverage in underserved regions. Mobile clinics hold the promise of ameliorating such inequities, although there is a paucity of studies that validate environmental infection in such facilities. Here, we describe community-based management of COVID-19 through a Smart Pod mobile clinic deployed in an underserved community area in the United States (Aldine, Harris County, TX, USA). In particular, we validate infection control and biological decontamination of the Smart Pod by testing surfaces and the air-filtration system for the COVID-19 virus and bacterial pathogens. We show the Smart Pod to be efficacious in providing a safe clinical environment for vaccine delivery. Moreover, in the Smart Pod, up-to-date education of community healthcare workers was provided to reduce vaccine hesitancy and improve COVID-19 vaccine uptake. The proposed solution has the potential to augment existing hospital capacity and combat the COVID-19 pandemic locally and globally.

Fear of COVID-19 and Trust in the Healthcare System Mediates the Association between Individual's Risk Perception and Preventive COVID-19 Behaviours among Iranians

Problems caused by the novel coronavirus disease-2019 (COVID-19) and its mutations have brought challenges in pandemic control for all countries worldwide. The present study examines the mediating roles of fear of COVID-19 and trust in the healthcare system in the association between individual’s risk perception and performing preventive COVID-19 behaviours among Iranians. A cross-sectional study design was used to collect data from 3652 residents of Qazvin province in Iran from 3 February to 15 April 2021 using a multistage stratified cluster sampling method. Participants responded to an online questionnaire concerning their fear of COVID-19, risk perception, trust in the healthcare system, and preventive COVID-19 behaviours. Small to medium positive interrelationships were observed between the variables of the study. Fear of COVID-19, trust in the healthcare system or both (fear of COVID-19 and trust in the healthcare system) mediated the association between an individual’s risk perception and performing preventive COVID-19 behaviours. The study demonstrated there are at least four ways through which an individual’s risk perception can influence preventive COVID-19 behaviours. Therefore, clinicians, health communicators, and researchers may capitalize on these findings to enhance preventive COVID-19 behaviours to help mitigate the spread of COVID-19 infection.

Food Safety and Employee Health Implications of COVID-19: A Review

The COVID-19 pandemic has greatly impacted the U.S. food supply and consumer behavior. Food production and processing are being disrupted as illnesses, proactive quarantines, and government-mandated movement restrictions cause labor shortages. In this environment, the food industry has been required to adopt new, additional practices to minimize the risk of COVID-19 cases and outbreaks among its workforce. Successfully overcoming these challenges requires a comprehensive approach that addresses COVID-19 transmission both within and outside the facility. Possible interventions include strategies (i) to vaccinate employees, (ii) to assure that employees practice social distancing, (iii) to assure that employees wear face coverings, (iv) to screen employees for COVID-19, (v) to assure that employees practice frequent hand washing and avoid touching their faces, (vi) to clean frequently touched surfaces, and (vii) to assure proper ventilation. Compliance with these control strategies must be verified, and an overall COVID-19 control culture must be established to implement an effective program. Despite some public misperceptions about the health risk of severe acute respiratory syndrome coronavirus 2 on foods or food packaging, both the virus biology and epidemiological data clearly support a negligible risk of COVID-19 transmission through food and food packing. However, COVID-19 pandemic-related supply chain and workforce disruptions and the shift in resources to protect food industry employees from COVID-19 may increase the actual food safety risks. The goal of this review was to describe the COVID-19 mitigation practices adopted by the food industry and the potential impact of these practices and COVID-19-related disruptions on the industry's food safety mission. A review of these impacts is necessary to ensure that the food industry is prepared to maintain a safe and nutritious food supply in the face of future global disruptions.

A critical review of heating, ventilation, and air conditioning (HVAC) systems within the context of a global SARS-CoV-2 epidemic

The Coronavirus disease (COVID-19) has spread over the world, resulting in more than 225 million patients, and 4.7 million deaths in September 2021. It also caused panic and terror, halted numerous activities, and resulted in the world economy deteriorates. It altered human behavior and compelled people to alter their lifestyles to avoid infection. Air conditioning systems are one of the most important sectors that must be considered because of the pandemic SARS-CoV-2 all over the world. Air is used as a heat transfer medium in heating, ventilation, and air conditioning (HVAC) systems. The air contains a variety of pollutants, viruses, and bacteria, all of which have an impact on and destroy human life. Significantly in summer, people spend more time in air conditioners which results in lower levels of vitamin D and melatonin which may affect the functioning of their immune system and are susceptible to receiving SARS-CoV-2 from other individuals. As an important component of air conditioning and ventilation systems, the air filter plays a significant role. As a result, researchers must work harder to improve its design to prevent the ultra-small particles loaded with COVID-19. This paper contributes to the design of existing HVAC systems in terms of their suitability and impact on the spread of the hybrid SARS-CoV-2 epidemic, as well as efforts to obtain a highly efficient air filter to remove super-sized particles for protection against epidemic infection. In addition, important guideline recommendations have been extracted to limit the spread of the SARS-CoV-2 throughout the world and to get the highest quality indoor air in air-conditioned places.

Psychological responses and associated factors during the initial stage of the coronavirus disease (COVID-19) epidemic among the adult population in Poland - a cross-sectional study

INTRODUCTION

The study aimed to assess the emotional state, the occurrence of symptoms of depression, anxiety, and stress, as well as the quality of life of adults living in Poland during the first weeks of the COVID-19 pandemic.

METHOD

The study was conducted on a group of 700 people aged 18 and over living in Poland. An anonymous online questionnaire was used in this cross-sectional study. The psychological impact of COVID-19 was measured using the Revised Event Impact Scale (IES-R) and the Depression, Anxiety, and Stress Scale (DASS - 21). The quality of life was assessed using the WHOQOL-BREF.

RESULTS

In Poland, a high average level of post-traumatic stress was found as a result of the COVID-19 pandemic, with at least the minimum level occurring in all surveyed people. There was also a high incidence of depression (48.00%), anxiety (39.29%), and stress (54.86) in the first phase of the pandemic. The average level of quality of life in Poland was the lowest for the physical domain and amounted to 49.56 (SD = 11.71). The standard of living in the psychological domain was 60.26 (SD = 13.14).

CONCLUSIONS

The pandemic is having a significant impact on human mental health. The very high average levels of post-traumatic stress, stress, anxiety, and depression as well as low quality of life make it necessary to consider interventions that will favor the use of more adaptive defense mechanisms and build mental resilience during an infectious disease pandemic and its long-term consequences.

The effect of increasing indoor ventilation on artificially generated aerosol particle counts

The COVID-19 global pandemic has caused millions of infections and deaths despite mitigation efforts that involve physical distancing, mask-wearing, avoiding indoor gatherings and increasing indoor ventilation. The purpose of this study was to compare ways to improve indoor ventilation and assess its effect on artificially generated aerosol counts. It was hypothesized that inbuilt kitchen vents would be more effective in reducing indoor aerosol counts than opening windows alone. A fixed amount of saline aerosol was dispersed in the experimental area using a nebulizer under constant temperature and a narrow range of humidity. A laser air quality monitor was used to record small particle counts every 30 minutes from baseline to 120 minutes for four different experimental groups for each combination of kitchen vents and windows. The results of the study demonstrate that aerosol counts were lowest with the kitchen exhaust vents on. This study suggests that liberal use of home exhaust systems like the kitchen vents could achieve significantly more air exchange than open windows alone and may present an effective solution to improving indoor ventilation, especially during the colder months when people tend to congregate indoors in closed spaces. There were no safety concerns involved when conducting this experiment.

Improved estimates of 222 nm far-UVC susceptibility for aerosolized human coronavirus via a validated high-fidelity coupled radiation-CFD code

Transmission of SARS-CoV-2 by aerosols has played a significant role in the rapid spread of COVID-19 across the globe. Indoor environments with inadequate ventilation pose a serious infection risk. Whilst vaccines suppress transmission, they are not 100% effective and the risk from variants and new viruses always remains. Consequently, many efforts have focused on ways to disinfect air. One such method involves use of minimally hazardous 222 nm far-UVC light. Whilst a small number of controlled experimental studies have been conducted, determining the efficacy of this approach is difficult because chamber or room geometry, and the air flow within them, influences both far-UVC illumination and aerosol dwell times. Fortunately, computational multiphysics modelling allows the inadequacy of dose-averaged assessment of viral inactivation to be overcome in these complex situations. This article presents the first validation of the WYVERN radiation-CFD code for far-UVC air-disinfection against survival fraction measurements, and the first measurement-informed modelling approach to estimating far-UVC susceptibility of viruses in air. As well as demonstrating the reliability of the code, at circa 70% higher, our findings indicate that aerosolized human coronaviruses are significantly more susceptible to far-UVC than previously thought.

Factors affecting aerosol SARS-CoV-2 transmission via HVAC systems; a modeling study

The role of heating, ventilation, and air-conditioning (HVAC) systems in the transmission of SARS-CoV-2 is unclear. To address this gap, we simulated the release of SARS-CoV-2 in a multistory office building and three social gathering settings (bar/restaurant, nightclub, wedding venue) using a well-mixed, multi-zone building model similar to those used by Wells, Riley, and others. We varied key factors of HVAC systems, such as the Air Changes Per Hour rate (ACH), Fraction of Outside Air (FOA), and Minimum Efficiency Reporting Values (MERV) to examine their effect on viral transmission, and additionally simulated the protective effects of in-unit ultraviolet light decontamination (UVC) and separate in-room air filtration. In all building types, increasing the ACH reduced simulated infections, and the effects were seen even with low aerosol emission rates. However, the benefits of increasing the fraction of outside air and filter efficiency rating were greatest when the aerosol emission rate was high. UVC filtration improved the performance of typical HVAC systems. In-room filtration in an office setting similarly reduced overall infections but worked better when placed in every room. Overall, we found little evidence that HVAC systems facilitate SARS-CoV-2 transmission; most infections in the simulated office occurred near the emission source, with some infections in individuals temporarily visiting the release zone. HVAC systems only increased infections in one scenario involving a marginal increase in airflow in a poorly ventilated space, which slightly increased the likelihood of transmission outside the release zone. We found that improving air circulation rates, increasing filter MERV rating, increasing the fraction of outside air, and applying UVC radiation and in-room filtration may reduce SARS-CoV-2 transmission indoors. However, these mitigation measures are unlikely to provide a protective benefit unless SARS-CoV-2 aerosol emission rates are high (>1,000 Plaque-forming units (PFU) / min).

Current challenges in COVID-19 diagnosis: a narrative review and implications for clinical practice

Early diagnosis of coronavirus disease 2019 (COVID-19) is crucial to early treatment and quarantine measures. In this narrative review, diagnostic tools for COVID-19 diagnosis and their main critical issues were reviewed. The COVID-19 real-time reverse transcriptase-polymerase chain reaction (RT-PCR) test is considered the gold standard test for the qualitative and quantitative detection of viral nucleic acid. In contrast, tests can be used for epidemiological surveys on specific communities, including occupational cohorts, but not for clinical diagnosis as a substitute for swab tests. Computed tomography (CT) scans can be useful for the clinical diagnosis of COVID-19, especially in symptomatic cases. The imaging features of COVID-19 are diverse and depend on the stage of infection after the onset of symptoms. CT sensitivity seems to be higher in patients with positive RT-PCR. Conventional chest sensitivity shows a lower sensitivity. An important diagnostic screening tool is ultrasounds, whose specificity and sensitivity depend on disease severity, patient weight, and operator skills. Nevertheless, ultrasounds could be useful as a screening tool in combination with clinical features and molecular testing to monitor disease progression. Clinical symptoms and non-specific laboratory findings may be useful if used in combination with RT-PCR test and CT-scanning.

A One-Year Prospective Study of Work-Related Mental Health in the Intensivists of a COVID-19 Hub Hospital

The COVID-19 pandemic has severely tested the physical and mental health of health care workers (HCWs). The various stages of the epidemic have posed different problems; consequently, only a prospective study can effectively describe the changes in the workers' health. This repeated cross-sectional study is based on a one-year investigation (spring 2020 to spring 2021) of intensive care physicians in one of the two COVID-19 hub hospitals in Central Italy and aims to study the evolution of the mental health status of intensivists during the pandemic. Changes in their work activity due to the pandemic were studied anonymously together with their perception of organisational justice, occupational stress, sleep quality, anxiety, depression, burnout, job satisfaction, happiness, and intention to quit. In May-June 2021, one year after the baseline, doctors reported an increased workload, isolation at work and in their social life, a lack of time for physical activity and meditation, and compassion fatigue. Stress was inversely associated with the perception of justice in safety procedures and directly correlated with work isolation. Occupational stress was significantly associated with anxiety, depression, burnout, dissatisfaction, and their intention to quit. Procedural justice was significantly associated with happiness. Doctors believed vaccinations would help control the problem; however, this positive attitude had not yet resulted in improved mental health. Doctors reported high levels of distress (73%), sleep problems (28%), anxiety (25%), and depression (64%). Interventions to correct the situation are urgently needed.

Occupational Health and Safety Measures in Healthcare Settings during COVID-19: Strategies for Protecting Staff, Patients and Visitors

The COVID-19 (SARS-CoV-2) pandemic has profoundly impacted almost every aspect of healthcare systems worldwide, placing the health and safety of frontline healthcare workers at risk, and it still continues to remain an important public health challenge. Several hospitals have put in place strategies to manage space, staff, and supplies in order to continue to deliver optimum care to patients while at the same time protecting the health and safety of staff and patients. However, the emergence of the second and third waves of the virus with the influx of new cases continue to add an additional level of complexity to the already challenging situation of containing the spread and lowering the rate of transmission, thus pushing healthcare systems to the limit. In this narrative review paper, we describe various strategies including administrative controls, environmental controls, and use of personal protective equipment, implemented by occupational health and safety departments for the protection of healthcare workers, patients, and visitors from SARS-CoV-2 virus infection. The protection and safeguard of the health and safety of healthcare workers and patients through the implementation of effective infection control measures, adequate management of possible outbreaks and minimization of the risk of nosocomial transmission is an important and effective strategy of SARS-CoV-2 pandemic management in any healthcare facility. High quality patient care hinges on ensuring that the care providers are well protected and supported so they can provide the best quality of care to their patients.

The role of airborne particles and environmental considerations in the transmission of SARS-CoV-2

Corona Virus Disease 2019 (COVID-19) caused by the novel coronavirus, results in an acute respiratory condition coronavirus 2 (SARS-CoV-2) and is highly infectious. The recent spread of this virus has caused a global pandemic. Currently, the transmission routes of SARS-CoV-2 are being established, especially the role of environmental transmission. Here we review the environmental transmission routes and persistence of SARS-CoV-2. Recent studies have established that the transmission of this virus may occur, amongst others, in the air, water, soil, cold-chain, biota, and surface contact. It has also been found that the survival potential of the SARS-CoV-2 virus is dependent on different environmental conditions and pollution. Potentially important pathways include aerosol and fecal matter. Particulate matter may also be a carrier for SARS-CoV-2. Since microscopic particles can be easily absorbed by humans, more attention must be focused on the dissemination of these particles. These considerations are required to evolve a theoretical platform for epidemic control and to minimize the global threat from future epidemics.

Addressing COVID-19 contagion through the HVAC systems by reviewing indoor airborne nature of infectious microbes: Will an innovative air recirculation concept provide a practical solution?

As the world continues to grapple with the reality of coronavirus disease, global research communities are racing to develop practical solutions to adjust to the new challenges. One such challenge is the control of indoor air quality in the COVID-19 era and beyond. Since COVID-19 became a global pandemic, the "super spread" of the virus has continued to amaze policymakers despite measures put in place by public health officials to sensitize the general public on the need for social distancing, personal hygiene, etc. In this work, we have reviewed the literature to demonstrate, by investigating the historical and present circumstances, that indoor spread of infectious diseases may be assisted by the conditions of the HVAC systems. While little consideration has been given to the possibility of indoor airborne transmission of the virus, the available reports have demonstrated that the virus, with average aerodynamic diameter up to 80-120 nm, is viable as aerosol in indoor atmosphere for more than 3 h, and its spread may be assisted by the HVAC systems. Having reviewed the vulnerability of the conventional ventilation systems, we recommend innovative air circulation concept supported by the use of UVGI in combination with nanoporous air filter to combat the spread of SARS-CoV-2 and other harmful microbes in enclosed spaces.

Impact on airborne virus behavior by an electric heat pump (EHP) operation in a restaurant during winter season

The world is having an unprecedented time due to the pandemic. Currently, more than 93 million people have been infected, and over 2 million people have passed away since 2020. SARS-CoV-2 has forced people to change their lifestyles and patterns. Under the pandemic, buildings are no longer safe shelters. The infected transmit infectious viruses to other occupants by direct contact or indirect contact (i.e., indoor airflow). In addition, the airflow from electric heat pump systems can propel indirect contact in indoor spaces. However, the impact of airflow is still not sufficiently identified to develop virus control strategies in buildings. Therefore, this study selected a restaurant in Seoul, Korea, to experiment with airborne virus transmission of direct airflow in winter using virus-similar particles. The results of this study verified the potential exposure of droplets or aerosols to occupants that can be delivered by air current from heating systems in winter. The effect of kitchen hoods was also confirmed as additional ventilation equipment without additional budget investment in restaurants. The recommendations of this study are expected to improve the guidelines for restaurants to ensure occupant's safety during the COVID-19 period.

COVID-19 and heat waves: New challenges for healthcare systems

Heat waves and Covid-19 overlap, as this pandemic continues into summer 2021. Using a narrative review, we identified overlapping risk groups and propose coping strategies. The high-risk groups for heat-related health problems as well as for high-risk COVID-19 groups overlap considerably (elderly with pre-existing health conditions). Health care facilities will again be challenged by Covid-19 during heat waves. Health care personnel are also at risk of developing heat related health problems during hot periods due to the use of personal protective equipment to shield themselves from SARS-CoV-2 and must therefore be protected from excessive heat periods. Some existing recommendations for heat health protection contradict recommendations for COVID-19 protection. This paper provides a preliminary overview of possible strategies and interventions to tackle these ambiguities. The existing recommendations for protection against heat-related illnesses need revisions to determine whether they include essential aspects of infection control and occupational safety and how they may be supplemented.

Psychosocial, emotional and professional challenges faced by female healthcare professionals during the COVID-19 outbreak in Lahore, Pakistan: a qualitative study

Background

The novel coronavirus disease (COVID-19) is spreading rapidly, increasing the stress and challenges for healthcare professionals around the world. This study aims to discover the psychosocial, emotional and professional challenges faced by female healthcare professionals (HCPs) treating COVID-19 patients in Pakistan.

Methods

Using an empirical phenomenological methodology, semi-structured telephone-based qualitative interviews were conducted with 22 female HCPs who were providing their expertise for COVID-19 patients in tertiary-level hospitals in Lahore, Pakistan. Purposive sampling was used for recruitment. The interviews were conducted between 20 July and 20 August 2020. The interviews were analysed using thematic analysis.

Results

This study explored the psychosocial, emotional and professional challenges faced by female HCPs serving COVID-19 patients. Five themes were observed in the interviews: apprehension while treating COVID-19 patients; feelings towards COVID-19 patients; challenges as female HCPs and coping strategies; confidence in government, administration and self-reflection; and finally, future concerns and recommendations. Many of these themes have also been linked with cultural issues, making the results specific to Pakistan.

Conclusions

During the COVID-19 pandemic, female frontline HCPs have faced immense psychosocial pressure, ranging from unsupportive family norms to an unwelcoming working environment and insensitive hospital administrations. Moreover, rumours among the general public, lack of proper training, missing incentives and improper system surveillance have increased the anxiety and stress among HCPs. Hence, legislators are advised to take appropriate actions countrywide in order to alleviate the still ongoing challenges and support female HCPs in their working environment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12905-021-01344-y.

Could thermodynamics and heat and mass transfer research produce a fundamental step advance toward and significant reduction of SARS-COV-2 spread?

We are living an extraordinary season of uncertainty and danger, which is caused by SARS-Cov-2 infection and consequent COVID-19 infection. This preliminary study comes from both a mix of entrepreneurial experience and scientific research. It is aimed by the exigency to reach a new and more effective analysis of the risks on the filed and to reduce them inside a necessary cooperation process which may regard both research and some of the economic activities which are damaged by passive protection measures such as indiscriminate lockdowns. This global emergency requires specific efforts by any discipline that regards specific problems which need to be solved urgently. The characteristic airborne diffusion patterns of COVID-19 shows that the airborne presence of viruses depends on multiple factors which include the dimension of microdroplets emitted by a contagious person, the atmospheric temperature and humidity, the presence of atmospheric particulate and pollution, which may act as a transport vehicle for the virus. The pandemic diffusion shows a particular correlation with the air quality and levels of atmospheric pollution. Specific problems need to solved to understand better the virus, its reliability, diffusion, replication, how it attacks the persons and the conditions, which drives to both positive and deadly evolution of the illness. Most of these problems may benefit from the contribution from both heat and mass transfer and the unsteady thermodynamics of living systems which evolves according to constructal law. After the bibliographic research on the virus, emissive and spread modes, and consequent today adopted protection, a detailed analysis of the contributions which may be assessed by research in thermodynamics, heat and mass transfer, technical and chemical physics. Some possible areas of research have been identified and discussed to start an effective mobilization which may support the effort of the research toward a significant reduction of the impacts of the pandemic infection and the economic risks of new generalized lockdowns.

Air Disinfection for Airborne Infection Control with a Focus on COVID-19: Why Germicidal UV is Essential†

Aerosol transmission is now widely accepted as the principal way that COVID-19 is spread, as has the importance of ventilation-natural and mechanical. But in other than healthcare facilities, mechanical ventilation is designed for comfort, not airborne infection control, and cannot achieve the 6 to 12 room air changes per hour recommended for airborne infection control. More efficient air filters have been recommended in ventilation ducts despite a lack of convincing evidence that SARS-CoV-2 virus spreads through ventilation systems. Most transmission appears to occur in rooms where both an infectious source COVID-19 case and other susceptible occupants share the same air. Only two established room-based technologies are available to supplement mechanical ventilation: portable room air cleaners and upper room germicidal UV air disinfection. Portable room air cleaners can be effective, but performance is limited by their clean air delivery rate relative to room volume. SARS-CoV-2 is highly susceptible to GUV, an 80-year-old technology that has been shown to safely, quietly, effectively and economically produce the equivalent of 10 to 20 or more air changes per hour under real life conditions. For these reasons, upper room GUV is the essential engineering intervention for reducing COVID-19 spread.

Determinants of Confidence in Overall Knowledge About COVID-19 Among Healthcare Workers in South Africa: Results From an Online Survey

Background: Adequate information and knowledge about COVID-19 has been shown to induce the confidence and positive performance among healthcare workers (HCWs). Therefore, assessing the relationship between confidence in knowledge and associated factors among HCWs is vital in the fight against COVID-19. This paper investigates factors associated with HCWs' confidence in their overall knowledge about COVID-19 in South Africa in the early stages of the epidemic.

Methods: Data utilized in this paper were from an online survey conducted among HCWs using a structured questionnaire on a data free online platform. The study population were all the medical fraternity in South Africa including medical and nurse practitioners as well as other healthcare professionals. Bivariate and multivariate logistic regression models were performed to examine the factors associated with confidence in HCWs' overall knowledge about COVID-19.

Results: Overall, just below half (47.4%) of respondents indicated that they had confidence in their overall knowledge about COVID-19. Increased odds of having confidence in the knowledge about COVID-19 were significantly associated with being male [aOR = 1.31 95% CI (1.03–1.65), p < 0.05], having a doctorate degree [aOR = 2.01 (1.23–3.28), p < 0.05], being satisfied with the information about COVID-19 guidelines [aOR = 6.01 (4.89–7.39), p < 0.001], having received training in 6–8 areas [aOR = 2.54 (1.89–3.43), p < 0.001] and having received training in 9–11 areas [aOR = 5.33 (3.81–7.47), p < 0.001], and having already treated COVID-19 patients [aOR = 1.43 (1.08–1.90), p < 0.001]. Those who were highly concerned with the levels of training of HCWs [aOR = 0.47 (0.24–0.92), p < 0.05] had decreased odds of having confidence in their overall knowledge about COVID-19.

Conclusion: This study sheds light on the importance of capacitating HCWs with knowledge and adequate relevant training as part of infection prevention control measures during pandemics. Future training and information sharing should be sensitive to knowledge gaps by age, gender, qualifications, professional categories, and experience.

SARS-CoV-2 Disease through Viral Genomic and Receptor Implications: An Overview of Diagnostic and Immunology Breakthroughs

The SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), which is believed to have originated in China towards the end of November 2019, has now spread across the globe, causing a pandemic in 192 countries. The World Health Organization has called it the SARS-CoV-2 pandemic. Rapid dissemination of the virus occurs mainly through the saliva (Flügge's droplets) and aerosol, together with nasal and lachrymal passages. The literature associated with the recent advancement in terms of rapid diagnostics and SARS-CoV-2 vaccines has thoroughly studied the role of ACE2 receptors and Furin, as well as viral agent access into the host cell and its significant persistence at the level of the oral mucosa, which represents the main access to the virus. The purpose of this review was to underline the processes of SARS-CoV-2 infection mechanisms and novel breakthroughs in diagnostics and vaccines. Different technologies, such as the RT-PCR molecular test and the antigenic test, have been developed to identify subjects affected by the SARS-CoV-2 in order to improve the tracking of infection geographical diffusion. Novel rapid and highly sensitive diagnostic tests has been proposed for the detection of SARS-CoV-2 to improve the screening capability of suspected contagions. The strengthening of the vaccination campaign represents the most effective means to combat the SARS-CoV-2 infection and prevent severe manifestations of the virus-different classes of vaccines have been developed for this purpose. Further attention on the novel SARS-CoV-2 variant is necessary in order to verify the protection efficacy and virulence reduction of the infective agent in the recent vaccine campaign.

Behavioral changes before lockdown and decreased retail and recreation mobility during lockdown contributed most to controlling COVID-19 in Western countries

BACKGROUND

The COVID-19 pandemic has prompted a lockdown in many countries to control the exponential spread of the SARS-CoV-2 virus, hereby reducing the time-varying basic reproduction number (Rt) to below one. Governments are looking for evidence to balance the demand of their citizens to ease some of the restriction, against the fear of a new peak in infections. In this study, we wanted to quantify the relative contribution of mobility restrictions, and that of behavioral changes that occurred already before the lockdowns, on the reduction of transmission during lockdowns in Western countries in early 2020.

METHODS

Incidence data of cases and deaths from the first wave of infections for 35 Western countries (32 European, plus Israel, USA and Canada) were analyzed using epidemiological compartment models in a Bayesian framework. Mobility data was used to estimate the timing of changes associated with a lockdown, and was correlated with estimated reductions of Rt.

RESULTS

Across all countries, the initial median estimate for Rt was 3.6 (95% IQR 2.4-5.2), and it was reduced to 0.78 (95% IQR 0.58-1.01) during lockdown. 48% (18-65%) of the reduction occurred already in the week before lockdown, with lockdown itself causing the remaining drop in transmission. A lower Rt during lockdown was independently associated with an increased time spent at home (0.21 per 10% more time, p < 0.007), and decreased mobility related to retail and recreation (0.07 per 10% less mobility, p < 0.008).

CONCLUSIONS

In a Western population unaware of the risk, SARS-CoV-2 can be highly contagious with a reproduction number R0 > 5. Our results are consistent with evidence that recreational activities (including restaurant and bar visits) enable super-spreading events. Exiting from lockdown therefore requires continued physical distancing and tight control on this kind of activities.