On February 8, at a press conference on the epidemic prevention and control of the Shanghai Municipal Government, health and epidemic prevention experts said that currently there are three ways that coronavirus transmission takes place: aerosol transmission, direct transmission, and contact transmission.
1. Aerosol transmission
Aerosol refers to fine solid particles or liquid droplets suspended in the air. These particles are stable and dispersed, and are invisible to the naked eye. The well-known droplet transmission means that when a patient sneezes, coughs, or speaks, the droplets containing the virus spray out and enter the eyes, nose, or mouth of others, causing infection.
As the droplets are large in size, they cannot stay in the air for too long. They will quickly fall to the ground and not make contact with the mouth and nose. However, after the sprayed droplets evaporate, residual nuclei can be left on the spot that the droplet hit. If the virus-contaminated droplet nuclei or dust particles can be suspended in the air for a long time, inhalation of either will cause infection, which is the aerosol transmission.
The difference between aerosol transmission and droplet transmission is the distance and time of transmission. Droplet transmission is close-range, but aerosol spray travels long distances, increasing the risk of contactless transmission. For example, in a hall, an infected person may talk or simply exhale and spread the virus to unconnected people more than 30 feet away.
2. Direct transmission
Direct transmission can take place during a kiss, sexual contact, or close conversations, all of which can spread the virus directly. Direct transmission usually occurs between family members and close friends.
3. Contact transmission
Contact transmission refers to touching a contaminated object and becoming infected. Under normal circumstances, when the droplets coughed out by a patient fall onto surrounding surfaces, the viruses in the droplets do not die immediately. The coronavirus can live for up to nine hours.
Later, if someone touches the virus-contaminated object with their hands — such as a table, door handle, etc. — and then touches their mouth, nose, or eyes, it is very likely to pass on the infection.
To prevent indirect contact transmission, hand washing and disinfection are the most crucial. Before touching your face with your hands, wash your hands with soap or use an alcohol-based hand gel and regularly disinfect the following most commonly used surfaces:
● Door handle, table, bed, chair
● Surface of toilet and sink
● Bowl, plate, cup
● Computer keyboard, mouse, mobile phone
● Children’s toys
Translated by Jean Chen and edited by Helen