Keeping social distance is one of the main measures to protect people from contracting coronavirus disease 2019 (COVID-19) infection.1 This measure is essential especially in the absence of an effective vaccine and effective treatments at this point in time. The World Health Organization recommends people keep at least 1 m (3 feet) apart.2 Based on the fact that a safe social distance is influenced by a variety of factors, a previous study has found that 1.83 m is the minimum requirement for preventing of contracting Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2).3 Furthermore, the wind speed in open space could significantly affect the travel distance of airborne disease-carrying droplets. When wind speed increases from 4 km/h to 15 km/h, the saliva droplet can travel up to 6 m with a corresponding decrease of its concentrations and liquid droplet size.4 Based on the existing study results, small particles with viral content may cover a distance of up to 10 m in an indoor environment,1 , 5 which could increase the risk of SARS-CoV-2 transmission in the workplace. To boost the economy, many countries have gradually relaxed social restrictions, including curfews and stay-at-home orders, and promotes the process of resumption of work.6 However, this could increase the risk of transmission of the SARS-CoV-2 and brings more uncertainties because the COVID-19 pandemic situation is still serious. As the resumption of work increases the opportunities for people to interact, stricter restrictions on social distancing may be warranted. Even if vaccines are successfully developed in the future, effective social distance policy may still be needed.7 Thus, it is necessary for us to reassess the evidence for social distancing and to determine whether stricter measures are needed.
In conclusion, based on the previous studies, stricter social distance policies might be warranted, especially in the absence of effective vaccines and treatments. More attention on social distancing measures with high feasibility and high acceptability is needed, and more precise and targeted social distance policies (in an indoor or outdoor environment) are expected to be explored in the future.
References
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