Uncertainties about the transmission routes of 2019 novel coronavirus

The 2019 novel coronavirus (now named as SARS‐CoV‐2) caused an outbreak of SARS‐like illness in the late of December 2019. At present, the origin, susceptible population, and infection sources already have been clear.1, 2 However, the transmission routes, a key step to the epidemic control, have not yet been fully ascertained. Here, we focus on the potential transmission routes that have been investigated in the SARS‐CoV‐2 epidemic recently. SARS‐CoV‐2, similar to SARS and MERS, is predominantly spread via respiratory tract with high infectivity. It is commonly recognized that droplet transmission is the main route. Spread by aerosol is suspected to be another important route of transmission but unestablished now. Epidemiological experts, as well as the WHO, consider more evidence is needed to confirm.3 Besides, there are other routes except respiratory transmission. The previous study indicated that different human coronaviruses, such as SARS‐CoV and MERS‐CoV, can maintain infectious for a different time on inanimate surfaces.4 Meanwhile, it was reported that SARS‐CoV‐2 was also founded on the surface of the door handles, cell phones, and other items in the residential sites of confirmed cases.5 Therefore, individuals will be probably infected if they touch the nose, mouth, or eyes after contacting the contaminated items.