Transmission mode associated with coronavirus disease 2019: a review

OBJECTIVE: In late December 2019 in Wuhan (China), Health Commission reported a cluster of pneumonia cases of unknown etiology, subsequently isolated and named Severe Acute Respiratory Syndrome (SARS) Coronavirus 2 (CoV-2). In this review, the main transmission routes and causes of mortality associated with COVID-19 were investigated. MATERIAL AND METHODS: A review was carried out to recognize relevant research available until 10 April 2020. RESULTS: The main transmission routes of COVID-19 have been the following: animal to human and human-to-human pathways, namely: respiratory transmission; oro-fecal transmission; air, surface-human transmission. Transmission from asymptomatic persons, healthcare transmission, and interfamily transmission have been well documented. CONCLUSIONS: SARS-CoV-2 possesses powerful pathogenicity and transmissibility. It is presumed to spread primarily via respiratory droplets and close contact. The most probable transmission pathway is definitely the inter-human one. Asymptomatic patients seem to play a crucial role in spreading the infection. Because of COVID-19 infection pandemic potential, careful surveillance is essential to monitor its future host adaptation, viral evolution, infectivity, transmissibility, and pathogenicity in order to gain an effective vaccine and flock immunity and reduce mortality as soon and as much as it is possible.