First released on 22 May, 2020

In a recent study, it is projected that intermittent or prolonged social distancing may be necessary until the year 2022 (Kissler et al., 2020). Depending on the duration of the immunity towards the virus, the resurgence in the contagion could be possible as late as 2024 (Kissler et al., 2020). If the projections are correct, business operations will require short-term and sustainable long-term strategies to minimize and prevent the spread of the virus within the workplace. Currently, there is limited information on SARS-CoV-2 about how the virus is transmitted, how to minimize the rate of spread and infection amongst workers, how to decontamination of surfaces, and how to determine if a worker is at risk or is infected with the virus. The goal of this report is to inform businesses of how to reduce the spread of the infection in the workplace, and how to detect employees who are infected but display no symptoms of the virus. These issues, addressed in this report, are based on current SARS-CoV-2 literature as of May 19th, 2020. Finally, for the gaps in the SARS-CoV-2 literature, comparisons were made to the coronavirus family members, or general knowledge was applied to viral infections of the respiratory tract and lungs, all of which served as models within this report for the predicted outcome of interest.

Why are people infected with the virus?

Work areas and public places with confined spaces limits the distancing that can be achieved between people and increases the risk of the virus from spread amongst people. There are questions raised for maintaining 2 meters of distance, which may not be enough given recent distances measured for droplets containing the pathogen. Studies indicate that virus particles may travel up to 7 to 8 meters (Figure 1) depending on environmental conditions (e.g., temperature and humidity) (Bourouiba, 2020). Given that business have limited space for maintaining social distancing, such as in hallways and elevators, maintaining two meters or more in distance may not be feasible at all times. Additional factors affecting the likely hood of the virus spreading between individuals are the properties of the infecting virus, the circumstances of the infection, and the biological system of the host (Rouse and Sehrawat). Thus, if social distancing is not possible to maintain at all times, understanding who is more at risk of an infection is just as important, such that measures may be implemented to ensure their safety on the job.

Figure 1. Multiphase turbulent gas cloud from a human sneeze. Adapted from Bourouiba (2020).

Age is a risk factor for viral infections, which is correlated to neonates (i.e., infants) and the elderly. Infants are vulnerable to viral infections because they have an impaired innate signaling pathway, i.e., an immature immune system (Rouse and Sehrawat, 2010; Simon et al., 2015). As age advances, the immune system undergoes remodeling and eventually declines in function. For older adults, the immune system will reduce in function, and lead to an increase in the rate of morbidity and mortality (Rouse and Sehrawat, 2010). Thus, individuals at high risk of infection are the elderly and infants.

For adults, the health of an immune system determines the probability of infection. Factors that contribute to a lowered immunity are nutritional deficits, long-haul travel, extreme changes in the environment, heavy exercise, life stress, and sleep disruption (Walsh, 2018). Thus, these physical and psychological challenges imposed on the central nervous system determine the effectiveness of the immune response (Walsh, 2018).

In terms of diet, serval micronutrients are required for maintaining the immune response at the different stages of the inflammatory response. Nutrients such as vitamins (A, D, C, E, B6 and B12), folate, zinc, iron, copper and selenium ensure the proper function of physical and chemical barriers and immune cells against infection (Gombart, Pierre and Maggini, 2020). For example, vitamins (D, A, B6 and B12) and folate promote a balance between beneficial and pathogenic bacteria within the body; thereby, reducing the risk of infection. Vitamin C promotes collagen synthesis in epithelial tissue; thereby, maintaining the integrity of the physical barriers (e.g., skin and mucus membranes) (Pullar, Carr and Vissers, 2017). Antioxidants, such as vitamins C and E, protect the cell membranes from damage caused by reactive oxygen species, which are generated from the immune response and normal metabolism (Gombart, Pierre and Maggini, 2020). Selenium supplements for adults at 100 μg per day increases the production of IFNγ within an infected cell, which alerts the body of a viral replication (Broome et al., 2004). Finally, vitamins (B6, B12, C and E), folate, and zinc maintain or enhance the cytotoxic activity of natural killer cells for clearing cells infected with the virus (Maggini, Pierre and Calder, 2018; Wu et al., 2019). Thus, workers may take dietary supplements to promote a healthy immune system and improve the physical defense against viral infections.

What can be done to minimize the transmission of the virus within the work area?

Center of Disease and Control (CDC) has a list of recommendations to limit the spread of the virus on their website (CDC, 2020b, 2020a). The recommendations are based on knowledge of how the viruses spreads from person to person, i.e., close contact between the infected individual and the recipient. This occurs from the droplets produced from the respiratory tract when the infected individual coughs, sneezes or talks. The droplets containing the virus particles are then transmitted to another person via the mouth, nose or lungs. A list of recommendations by the CDC to minimize the transmission of the virus is outlined below.

1) The infected individual should stay at home if they show signs of fever

2) The infected individual should seek medical assistance, if the condition worsens, while avoiding public places/transportation.

3) Washing hands often with soap and water for at least 20 seconds, or alcohol disinfectant.

4) Avoid touching eyes, nose, and mouth with unwashed hands

5) Avoid close contact by maintaining 6 feet apart from the infected and asymptomatic individual.

6) Avoid mass gatherings and crowded places.

7) Wear a cloth to cover the nose and mouth, in order to minimize the spread to other people.

8) Cover mouth and nose when coughing or sneezing.

9) Discard tissues in the trash.

10) Immediately wash hands with soap and water (or alcohol disinfectant) after coughing or sneezing.

11) Everyday clean and disinfect “highly-touched” surfaces and objects.

Disinfectants known to inactivate the coronavirus

For cleaning and disinfecting “highly-touched” surfaces and objects, the United States Environmental Protection Agency has published a registry of approved disinfectants for use against viruses. Unfortunately, the registry is lacking disinfects proven to be effective against SARS-CoV-2 (i.e., COVID-19), or related coronavirus family (i.e., SARS-CoV and MERS-CoV). Within the registry of disinfectants, there are no viruses listed that are evolutionary related to the picornavirus supergroup that the coronavirus falls under, i.e., positive stranded RNA viruses. Additionally, the picornavirus supergroup lacks capsid homology with the coronavirus family (Wolf et al., 2018). Thus, the cleaning supplies listed in the EPA registry have no reports of its efficacy against SARS-CoV2, nor are there any viruses with a similar capsid structure as the coronavirus family members to use a viral model for the effectiveness of the disinfectant (Environmental Protection Agency, 2020).

Literature reports on the use of disinfectants against SARS-CoV, a related coronavirus to SARS-Cov-2, indicates that alcohol concentrations ranging from 70% to 95% (v/v) will reduce the viral titer by ≥99.3% (Tables 1 and 2). For handwashing, the results would suggest that the majority of the virus particles are inactivated by alcohol following a minimal contact time of 30 seconds of treatment (Rabenau, Cinatl, et al., 2005; Rabenau, Kampf, et al., 2005). For surface disinfectants, most of the virus particles are inactivated (≥99.9%) following a contact time of 30 minutes (Table 2). Thus, the values listed in Tables 1 and 2 can be translated into useful guidelines for selecting disinfectants and contact time for decontaminating hands and surfaces that contain the virus particles. Therefore, hand disinfectants for use against SARS-Cov2 should contain an alcohol concentration that is greater than 70% (v/v) with a contact time of 30 seconds, and a contract time of 30 minutes for surface disinfectants is recommended.

Table 1. The viricidal activity of different disinfectants against SARS-CoV after 30 seconds of treatment. The ratios for each treatment consisted of 8 parts treatment, 1 part viral suspension and 1 part fetal bovine serum. TCID50 is the 50% tissue culture infective doses. *Note, the treatment contact time was 60 seconds. The table was adapted from Rabenau, Cinatl, et al. (2005).

Table 2. The viricidal activity of different disinfectants against SARS-CoV after 30 seconds of treatment. *Note, the treatment exposure time was 30 minutes. TCID50 is the 50% tissue culture infective doses. The table was adapted from Rabenau, Kampf, et al. (2005).

Effects of temperature, relative humidity and surface composition on the inactivation of the coronavirus

The duration that a virus may persist within a work place is a concern for a business, if the virus is not eliminated from the work area following the decontamination, or if no actions are taken because it is not apparent that the work area is contaminated. A recent publication suggests that increasing the temperature of the environment can significantly decrease the number of SARS-CoV-2 particles that persist on a surface (Chin et al., 2020). The study showed that the virus can persist at 4°C for greater than 14 days (336 hours), 22°C for up to 7 days (168 hours), and 37°C for up to 1 day (Figure 2) (Chin et al., 2020). Thus, increasing the temperature of the environment can decrease the number of particles within the environment. To implement these findings in an office setting, then the increase in temperature needs to be within the recommended temperature range (e.g., 20°C to 26°C at a relative humidity level between 40 to 70%), where the temperature is dependent on the physical nature of the job, as outlined by Occupational Health and Safety Directive (CCOHS, 2018). If decontamination of materials is required, heating the material up to 56°C for 30 minutes, or up to 70°C for 5 minutes can effectively eliminate the virus from the material (Chin et al., 2020).

Figure 2. The effect of temperature on the stability of SARS-CoV-2. The tissue culture was infected with 6.8 log unit (TCID50/mL) of the virus culture, and was incubated up to 14 days, and then tested for its infectivity. The figure was modified from Chin et al. (2020).

Chin et al. (2020) also examined the half-life (t1/2) of SARS-CoV-2 on various surfaces. Analysis of the data suggests that the virus particles are less stable on tissue paper (t1/2 of 2.75 minutes; Moya, 2020, unpublished observations), and on glass (t1/2 of 4.8 hours; Figure 3) (Chin et al., 2020). The virus was found to persists for longer periods of time on the outer surface of a surgical mask (t1/2 of 23.9 hours), stainless steel (t1/2 of 14.7 hours), and plastic (t1/2 of 11.4 hours; Figure 3). If a work place is not decontaminated, and one were to apply 10 half-lives for a material to be considered decontaminated, then a tissue paper would be safe to handle after 27.5 minutes, while a surgical mask might be safe to use after 12.5 days. Thus, it would be advisable from a safety perspective for the intrepid individual to dispose of the contaminated material than to wait for an extended period of time such that the virus becomes inactivated.

Figure 3. The half-life of SARS-CoV-2 on various surfaces. The half-life of the virus particle residing on: 1) the outer surface of a surgical mask was 23.9 hours, 2) stainless steel was 14.7 hours, 3) plastic was 11.4 hours, 4) tissue paper was 2.75 minutes, and glass (not displayed) was 4.8 hours. The virus culture (18 ln unit of TCID50/mL) was pipetted onto a surface of a 1 cm2 per piece, and incubated at 22°C with a relative humidity of ~65%. The figure was modified from Chin et al. (2020).

Literature reports on the effect of humidity on SARS-CoV-2 are lacking. There is however information pertaining to a related coronavirus family member, i.e., alphacaronavirus 1, also known as Transmissible gastroenteritis virus, which infects pigs. The effect of relative humidity on the inactivation of the virus particles on a steel surface are as follows: 50% > 80% > 20% relative humidity (Casanova et al., 2010). Given the limitation in the range of relative humidity conditions tested, it is difficult propose an optimal humidity level for inactivating the virus. Additional constraints in setting the humidity levels at work are as follows: the risks of condensation on the surfaces of equipment and the development of mold when the relative humidity levels are above 70%; while less than 20% humidity levels leads to cracking of the cement foundation, build-up of static electricity, and drying of tissues (i.e., eyes, mucous membranes and skin) (CCOHS, 2018). If it is possible, maintaining the relative humidity within the work area at or near 50% is recommended, until further data is available in the literature.

How to detect a viral infection?

There is a need for accurate screening methods for detecting viral infections, especially for many international airports and business organizations to minimize the risk of transmission of infectious diseases. The use of infrared camera would be ideal for screening individuals because it does not involve contact of the probe to measure the body temperature of individuals (Ng, 2005). The area of study is currently facing limitations in sensitivity when monitoring the skin temperature, due to factors such as ambient temperature and/or alterations in people’s biochemistry (e.g., alcohol impairment and antipyretic substances)(Nakayama et al., 2015). To improve the accuracy of the device, additional infrared parameters are being incorporated into the measurements, such as ear temperature, respiration rate and heart rate, such that a higher accuracy is achieved (Sun et al., 2013; Nakayama et al., 2015). Thus, the technology requires further developments before it can be implemented as an effective screening technique for identifying infected individuals in the workplace.

A reliable method for measuring body temperature is the mercury-in-glass thermometer, a standard used for measuring human temperature for hundreds of years. To minimize contact with an individual, a tympanic (ear) infrared thermometer may be used for measuring the body temperature of individuals (Devrim et al., 2007). It was observed that clinical tympanic thermometer (e.g., First Temp Genius) have a 5% misdiagnosis of patients with a fever, while the home-use tympanic thermometer (e.g., Microlife IR IDA) have a 31% misdiagnosis of patients with a fever (Devrim et al., 2007). It was also observed that the temperature of the clinical tympanic thermometer was within the range limits (+0.98°C and -1.27°C ) of the home-use tympanic thermometers, when compared to the mean temperature of a mercury-in-glass thermometer. If a fever for a tympanic temperature is considered to be above 38.3°C, when using a mercury-in-glass thermometer. Then it is possible for an individual, who has no fever, to be misdiagnosed with a fever when using a clinical tympanic thermometer, because it is reading +0.5°C higher than a mercury-in-glass thermometer. Additionally, home-use tympanic thermometers is expected to have a higher misdiagnosis of a fever, because it is possible for the instrument to report a temperature +0.98°C higher than clinical mercury-in-glass thermometers. Thus, clinical infrared tympanic thermometers may lead to a 5% misdiagnosis for individuals with a fever, while infrared home-use tympanic thermometer have a 15% misdiagnosis for individuals with a fever. This results from the infrared instrument having a higher probability of obtaining a higher than expected temperature measurement when compared to the mercury-in-glass thermometer. If a company were to implement mandatory temperature readings of its employees, a clinical infrared tympanic thermometer would be recommended, because it is noninvasive and has less chance of misdiagnosis than a home-use tympanic thermometer.

It has been reported that fluctuations in baseline temperature, which differs among a group of individuals, is indicative of each person’s metabolic activity and weight (Martinez del Rio and Karasov, 2010; Obermeyer, Samra and Mullainathan, 2017). For example, body fat acts as an insulator and leads to higher heat retention for individuals with more fat (Obermeyer, Samra and Mullainathan, 2017). Therefore, when measuring the temperature of employees, it is important to know their baseline temperature, in order to improve the diagnostic method for determining if an individual has a fever.

Legal aspects for an employer

Basic human rights and labour safety laws are not covered in this review.

References

Bourouiba, L. (2020) ‘Turbulent Gas Clouds and Respiratory Pathogen Emissions: Potential Implications for Reducing Transmission of COVID-19’, JAMA — Journal of the American Medical Association, 323(18), pp. E1–E2.

Broome, C. S. et al. (2004) ‘An increase in selenium intake improves immune function and poliovirus handling in adults with marginal selenium status’, American Journal of Clinical Nutrition, 80(1), pp. 154–162.

Casanova, L. M. et al. (2010) ‘Effects of air temperature and relative humidity on coronavirus survival on surfaces’, Applied and Environmental Microbiology, 76(9), pp. 2712–2717.

CCOHS (2018) Thermal Comfort for Office Work, Canadian Centre for Occupational Health and Safety. Available at: https://www.ccohs.ca/oshanswers/phys_agents/thermal_comfort.html (Accessed: 20 May 2020).

CDC (2020a) Social Distancing, Quarantine, and Isolation, Centers for Disease Control and Prevention. Available at: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/social-distancing.html (Accessed: 20 May 2020).

CDC (2020b) What to do if you are sick, Centers for Disease Control and Prevention. Available at: https://www.cdc.gov/coronavirus/2019-ncov/if-you-are-sick/steps-when-sick.html (Accessed: 20 May 2020).

Chin, A. W. H. et al. (2020) ‘Stability of SARS-CoV-2 in different environmental conditions’, The Lancet Microbe. Elsevier Ltd, 1(1), p. e10. Available at: http://dx.doi.org/10.1016/S2666-5247(20)30003-3.

Devrim, I. et al. (2007) ‘Measurement Accuracy of Fever by Tympanic’, Pediatric Emergency Care, 23(1), pp. 16–19.

Environmental Protection Agency (2020) List N: Disinfectants for Use Against SARS-CoV-2 [database]. Available at: https://www.hsdl.org/?abstract&did=835337 https://www.epa.gov/pesticide-registration/list-n-disinfectants-use-against-sars-cov-2.

Gombart, A. F., Pierre, A. and Maggini, S. (2020) ‘A review of micronutrients and the immune system–working in harmony to reduce the risk of infection’, Nutrients, 12(1).

Kissler, S. M. et al. (2020) ‘Projecting the transmission dynamics of SARS-CoV-2 through the postpandemic period’, Science, (eabb5793), pp. 1–9. Available at: https://doi.org/10.1016/j.solener.2019.02.027%0Ahttps://www.golder.com/insights/block-caving-a-viable-alternative/%0A???

Maggini, S., Pierre, A. and Calder, P. C. (2018) ‘Immune function and micronutrient requirements change over the life course’, Nutrients, 10(10).

Martinez del Rio, C. and Karasov, W. H. (2010) ‘Body Size and Temperature : Why They Matter’, Nature Education Knowledge, pp. 1–7. Available at: https://www.nature.com/scitable/knowledge/library/body-size-and-temperature-why-they-matter-15157011/.

Nakayama, Y. et al. (2015) ‘Non-contact measurement of respiratory and heart rates using a CMOS camera-equipped infrared camera for prompt infection screening at airport quarantine stations’, 2015 IEEE International Conference on Computational Intelligence and Virtual Environments for Measurement Systems and Applications, CIVEMSA 2015. IEEE, pp. 11–14.

Ng, E. Y. K. (2005) ‘Is thermal scanner losing its bite in mass screening of fever due to SARS?’, Medical Physics, 32(1), pp. 93–97.

Obermeyer, Z., Samra, J. K. and Mullainathan, S. (2017) ‘Individual differences in normal body temperature: Longitudinal big data analysis of patient records’, BMJ (Online), 359, pp. 1–8.

Pullar, J. M., Carr, A. C. and Vissers, M. C. M. (2017) ‘The roles of vitamin C in skin health’, Nutrients, 9(8).

Rabenau, H. F., Kampf, G., et al. (2005) ‘Efficacy of various disinfectants against SARS coronavirus’, Journal of Hospital Infection, 61(2), pp. 107–111.

Rabenau, H. F., Cinatl, J., et al. (2005) ‘Stability and inactivation of SARS coronavirus’, Medical Microbiology and Immunology, 194(1–2), pp. 1–6.

Rouse, B. T. and Sehrawat, S. (2010) ‘Immunity and immunopathology to viruses: What decides the outcome?’, Nature Reviews Immunology. Nature Publishing Group, 10(7), pp. 514–526. Available at: http://dx.doi.org/10.1038/nri2802.

Simon, A. K. et al. (2015) ‘Evolution of the immune system in humans from infancy to old age’, Proc. Biol. Sci., 282(1821), pp. 1–12.

Sun, G. et al. (2013) ‘Development of an infection screening system for entry inspection at airport quarantine stations using ear temperature, heart and respiration rates’, Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS. IEEE, pp. 6716–6719.

Walsh, N. P. (2018) ‘Recommendations to maintain immune health in athletes’, European Journal of Sport Science. Taylor & Francis, 18(6), pp. 820–831.

Wolf, Y. I. et al. (2018) ‘Origins and evolution of the global RNA virome’, mBio, 9(6), pp. 1–31. doi: 10.1128/mBio.02329–18.

Wu, D. et al. (2019) ‘Nutritional modulation of immune function: Analysis of evidence, mechanisms, and clinical relevance’, Frontiers in Immunology, 10(JAN), pp. 1–19.