Why Measures to Prevent Community Spread of Coronavirus are Critical
David MacIntosh | March 24, 2020
Current directives to combat COVID-19 in the United States are based on limiting community spread of the novel coronavirus (SARS-CoV-2). The tactics include social distancing, frequent hand washing and related actions. But why is it that doctors, scientists, and other specialists have counseled government authorities to recommend these methods in particular?
Coronavirus (COVID-19): Why is this pandemic happening now?
The answer to that question lies in understanding the epidemiological context of the new coronavirus. (Epidemiology is the branch of public health that deals with the study of the causes, distribution, and control of disease in populations.) SARS-CoV-2 is community spread, which means the virus is transmitted from person-to-person rather than through food, water, or other environmental media.1 China, South Korea, and Singapore all effectively stifled transmission through a combination of aggressive testing of symptomatic individuals, isolation of SARS-CoV-2 carriers in dedicated zones, and physical distancing.2 Circumstances in the United States at present are different and therefore require a different combination of tactics to manage the public health impacts of this virus.
What We Know about the Transmission of Coronavirus
Unlike the nations that first encountered this virus, the United States does not yet have the capacity to test a majority of symptomatic patients for SARS-CoV-2 infection and may not have the will or authority to isolate known or suspected infected persons. Nor, is an antiviral treatment available to eliminate virus from infected persons. Therefore, our best option to control community spread at present is for all individuals to behave in a manner that minimizes the likelihood of person-to-person transmission.3 We have mounting evidence that infected persons are contagious before showing symptoms, thus the increasing strength of government directives for social distancing or physical spacing.4 In addition, we know that the symptoms of early-onset COVID-19 cannot be readily distinguished from those of influenza and the common cold, thus the guideline for self-isolation of symptomatic individuals. Further, we know SARS-CoV-2 can be transmitted to people who are in close contact with infected individuals, presumably through large droplets that travel only short distances, thus the 6-foot distancing guideline.1 We also know that infected persons who cough or sneeze into their hands and don’t wash them immediately could transmit infectious doses to other people through direct contact, thus the frequent handwashing guideline. We recognize the possibility, although not demonstrated empirically yet, of surface-mediated transmission, thus the frequent surface cleaning guideline.5 Similarly, we cannot rule out the possibility of aerosol transmission accounting for a small portion of new cases, although also not demonstrated yet, thus the recommendations for isolating infected persons to designated spaces within a home or hospital, maximizing outdoor air delivery, applying high-efficiency filtration, and negatively pressurizing isolation spaces, where feasible. And lastly, because people can carry and expel the virus but not have symptoms, more experts are recommending use of a mask while in public to capture liquids that may escape the mouth while coughing, sneezing, or talking.6 Basic dust masks, bandanas, and scarves are appropriate at this time for most people because respirators and surgical masks are currently in limited supply and are needed in clinical settings to minimize transmission from COVID-19 patients to caregivers.
Mitigating Community Spread of COVID-19 is Vital
Knowledge about transmission of the new coronavirus is growing rapidly and efforts to develop antiviral therapies to treat patients and vaccines to prevent infection are being pursued aggressively. The capacity to identify carriers of SARS-CoV-2 in the United States is growing, but not yet widely available. Continued use of self-directed tactics to mitigate community spread of SARS-CoV-2 remain the best option for addressing the incidence of COVID-19 and its impacts on public health.
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The coronavirus outbreak is evolving rapidly and over the course of time more information and data will become available. This post reflects information available as of the publication date.
- Bai et al. Presumed asymptomatic carrier transmission of COVID-19. Journal of the American Medical Association, February 21, 2020.
- van Dorelman et al. Aerosol and surface stability of HCoV-19 (SARS-CoV02) compared to SARS-CoV-1. New England Journal of Medicine. March 8, 2020.
- Gottlieb, Scott, Caitlin Rivers, Mark B. McClellan, Lauren Silvis, and Crystal Watson. “National Coronavirus Response: A Road Map to Reopening.” Report, American Enterprise Institute (AEI), March 28, 2020.