Environmental factors involved in SARS-CoV-2 transmission: effect and role of indoor environmental quality in the strategy for COVID-19 infection control

Abstract

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a new zoonotic agent that emerged in December 2019, causes coronavirus disease 2019 (COVID-19). This infection can be spread by asymptomatic, presymptomatic, and symptomatic carriers. SARS-CoV-2 spreads primarily via respiratory droplets during close person-to-person contact in a closed space, especially a building. This article summarizes the environmental factors involved in SARS-CoV-2 transmission, including a strategy to prevent SARS-CoV-2 transmission in a building environment. SARS-CoV-2 can persist on surfaces of fomites for at least 3 days depending on the conditions. If SARS-CoV-2 is aerosolized intentionally, it is stable for at least several hours. SARS-CoV-2 is inactivated rapidly on surfaces with sunlight. Close-contact aerosol transmission through smaller aerosolized particles is likely to be combined with respiratory droplets and contact transmission in a confined, crowded, and poorly ventilated indoor environment, as suggested by some cluster cases. Although evidence of the effect of aerosol transmission is limited and uncertainty remains, adequate preventive measures to control indoor environmental quality are required, based on a precautionary approach, because COVID-19 has caused serious global damages to public health, community, and the social economy. The expert panel for COVID-19 in Japan has focused on the “3 Cs,” namely, “closed spaces with poor ventilation,” “crowded spaces with many people,” and “close contact.” In addition, the Ministry of Health, Labour and Welfare of Japan has been recommending adequate ventilation in all closed spaces in accordance with the existing standards of the Law for Maintenance of Sanitation in Buildings as one of the initial political actions to prevent the spread of COVID-19. However, specific standards for indoor environmental quality control have not been recommended and many scientific uncertainties remain regarding the infection dynamics and mode of SARS-CoV-2 transmission in closed indoor spaces. Further research and evaluation are required regarding the effect and role of indoor environmental quality control, especially ventilation.

Phylodynamic analysis in the understanding of the current COVID-19 pandemic and its utility in vaccine and antiviral design and assessment

“…Some models under this family, add compartments, like the E compartment, under the SEIR model, that corresponds to Exposed individuals that do not spread the infection, since they have a latent asymptomatic infection but are not infectious, which is not the case for SARS-CoV-2 given that asymptomatic patients can also spread the disease ( Figure 2a ), and also, can consider the rate of becoming susceptible again after infection, as would be important in the case of reinfection ( Figure 2a ), a plausible but uncertain phenomenon in the case of SARS-CoV-2, 17 and the rate of infection from different human to human sources, like contaminated surfaces (sparking rate, Figure 2a ), as has been documented for SARS-CoV-2 and other viruses. 18

Figure 2. Schematic diagram of between-host (a) and intra-host virus (b) dynamics.

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

“…People may also become infected through physical contact of virus-contaminated objects such as solid waste ( Al Huraimel et al, 2020 , Ben-Shmuel et al, 2020 , Suman et al, 2020 ). Aerosol transmission in a relatively closed environment ( Azuma et al, 2020 , Zhao et al, 2020 , Tung et al, 2021 ), such as hospital locals have been confirmed ( Shi et al, 2020 ). In addition, environmental pollution caused by feces and urine aerosols ( Heller et al, 2020 ) or physical contact in toilets ( Hoseinzadeh et al, 2020 , Mehraeen et al, 2020 , Pamplona et al, 2020 ) could pose a major transmission risk.…”

“…Because of the high infectivity and mutability of COVID-19, the environmental transmission routes of SARS-CoV-2 are a subject of urgent research. Some studies identify the main routes of transmission as respiratory droplets ( Azuma et al, 2020 , Marin-Garcia et al, 2021 ) and close contact ( Martinez-Fierro et al, 2021 ). People may also become infected through physical contact of virus-contaminated objects such as solid waste ( Al Huraimel et al, 2020 , Ben-Shmuel et al, 2020 , Suman et al, 2020 ).…”

COVID-19 and chronic fatigue syndrome: Is the worst yet to come?

“…The outbreak of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a public health emergency of international concern [1] . The most common symptoms of patients with COVID-19 are fever, cough, shortness of breath, and myalgia/fatigue [1] . Anosmia (loss of smell) and dysgeusia (altered sensation of taste) have been reported in 33–80% of patients with COVID-19 [2] .…”

“…Anosmia (loss of smell) and dysgeusia (altered sensation of taste) have been reported in 33–80% of patients with COVID-19 [2] . SARS-CoV-2 is mainly transmitted human-to-human through close contact, respiratory droplets, fomites, and contaminated surfaces [1] . Importantly, a chronic post-viral syndrome characterized by chronic fatigue, variable nonspecific myalgia, depression and sleep disturbances has previously been reported following SARS coronavirus infection, which emerged from South East Asia in early 2003 [3] .…”