SARS-CoV-2 Transmission Channels: A Review of the Literature

BACKGROUND The novel coronavirus SARS-CoV-2 is responsible for the current global pandemic. There is a concerted effort within the global scientifi c community to identify (and thereby potentially mitigate) the possible modes of transmission through which the virus spreads throughout populations. OBJECTIVE Summarize the ways in which SARS-CoV-2 is transmitted and provide scientifi c support for the prevention and control of COVID-19. EVIDENCE AQUISITION We conducted an extensive literature search using electronic databases for scientifi c articles addressing SARSCoV-2 transmission published from December 28, 2019 through July 31, 2020. We retrieved 805 articles, but only 302 were included and discussed in this review. The report captured relevant studies investigating three main areas: 1) viral survival, 2) transmission period and transmissibility, and 3) routes of viral spread. DEVELOPMENT Currently available evidence indicates that SARSCoV-2 seems to have variable stability in different environments and is very sensitive to oxidants, such as chlorine. Temperature and humidity are important factors infl uencing viral survival and transmission. SARSCoV-2 may be transmitted from person to person through several different routes. The basic mechanisms of SARS-CoV-2 transmission person-to-person contact through respiratory droplets, or via indirect contact. Aerosolized transmission is likely the dominant route for the spread of SARS-CoV-2, particularly in healthcare facilities. Although SARS-CoV-2 has been detected in non-respiratory specimens, including stool, blood and breast milk, their role in transmission remains uncertain. A complicating factor in disease control is viral transmission by asymptomatic individuals and through what would otherwise be understood as innocuous human activities. CONCLUSIONS This article provides a review of the published research regarding human-to-human transmission of SARS-CoV-2 and insights into developing effective control strategies to stop viral propagation. KEYWORDS COVID-19, SARS-CoV-2, transmission, pandemics, microbial viability.