Click to expandUnderstanding the modes of transmission of infective agents, such as viruses and bacteria, is essential in better controlling the outbreaks that these infective agents can cause. Transmission of viruses varies, and could be affected by the quantities of virus the route of transmission allows, the size of the transport media, as well as the physical conditions affecting transmission, such as humidity, temperature, airflow, duration of exposure.
In the case of COVID-19, the current available evidence indicates that the virus (SARS-CoV-2) is transmitted from one person to another, either directly primarily through oral and respiratory secretions, or indirectly through contaminated surfaces. Other modes of transmission are being investigated, including animal-to-human and aerosol transmission. However, the evidence remains inconclusive. This is why, understanding how, when and in what types of settings SARS-CoV-2 spreads is critical to developing effective public health and infection prevention and control measures to break chains of transmission.
There have been reported outbreaks of COVID-19 observed in closed settings, such as restaurants, nightclubs, places of worship or places of work where people may be shouting, talking or singing. In these outbreaks, aerosol transmission, particularly in these indoor locations where there are crowded and inadequately ventilated spaces where infected persons spend long periods of time with others, cannot be ruled out.
From the current evidence, transmission of COVID-19 is primarily occurring from people when they have symptoms, and can also occur just before they develop symptoms, when they are in close proximity to others for prolonged periods of time. More evidence is needed for airborne transmission confirmation, especially in open spaces.
Data from Lebanon on COVID-19 cases reported have so far been linked mostly to direct contact with infected people, usually in clusters with known index case.
Related link
Q&A: How is COVID-19 transmitted?
Modes of transmission of virus causing COVID-19: implications for IPC precaution recommendations
