Transmission Modes of COVID-19: A Systematic Review

Background: The Coronavirus disease 2019 (COVID-19) is a highly contagious viral infection that was initiated in Wuhan, China, and has spread around the world. The high prevalence and rapid transmission between individuals of COVID-19 have become an international challenge that requires careful consideration. We aimed to review the current evidence of COVID-19 transmission modes. Methods: This study was a systematic review performed to identify current evidence of COVID-19 transmission modes. We searched selected keywords in six key databases to discover sources relevant to the main objective of the study. To identify studies meeting the inclusion criteria, the authors screened the titles and abstracts of the retrieved documents. The appropriate articles were then selected and their results were discussed to make the final inclusion. Results: We identified five potential transmission modes of COVID-19, including airborne, droplet, contact with contaminated surfaces, oral and fecal secretions. Furthermore, some studies have pointed out other modes of virus transmission, such as person to person, and direct contact with animals. Conclusion: Droplet and contact with contaminated surfaces are the most frequent transmission modes of COVID-19. However, fecal excretion, environmental contamination, and fluid pollution may also contribute to viral transmission. The possibility of fecal transmission in COVID-19 has implications, especially in areas that are poorly hygienic. Environmental pollution can be caused by patients with SARS-CoV-2 through respiratory droplets and feces. Consequently, the human environment will become a potential medium of virus transmission.