Research progress on transmission routes of COVID-19.

The COVID-19 (SARS-CoV-2) pandemic has become an urgent issue and attracted extensive attention all over the world due to its strong infectivity and high mortality. The outbreak of COVID-19 has a negative impact on the development of the world economy, brought inconvenience to people's daily life and threatened our health safety. Considering the global spread of COVID-19 disease with the tremendous number of infections and also deaths, understanding the transmission modes of this virus to formulate effective prevention and control strategies is of vital importance. This paper reviews three main transmission routes (contact, droplet and aerosol) and three possible transmission routes (maternal-infant, fecal-oral and cross-species) of COVID-19, which has reference value and guiding significance for the prevention and control of COVID-19 in the future.