A new assessment in the medical journal Lancet has found “consistent, strong evidence” that the SARS-CoV-2 virus, which causes Covid-19, is predominantly transmitted through the air.
Therefore, public health measures that fail to treat the virus as predominantly airborne leave people unprotected and allow the virus to spread, according to six experts from the UK, USA and Canada, including Jose-Luis Jimenez, a chemist at the Cooperative Institute for Research in Environmental Sciences (CIRES) and the University of Colorado Boulder.
Silent (asymptomatic or presymptomatic) transmission of SARS-CoV-2 from people who are not coughing or sneezing accounts for at least 40% of all transmission.
This silent transmission is a key way Covid-19 has spread around the world, “supporting a predominantly airborne mode of transmission,” as per the assessment.
“The evidence supporting airborne transmission is overwhelming, and evidence supporting large droplet transmission is almost non-existent,” Jimenez said. “It is urgent that the World Health Organisation and other public health agencies adapt their description of transmission to the scientific evidence so that the focus of mitigation is put on reducing airborne transmission.”
Further, the researchers emphasises that while it is necessary to wash hand and clean surfaces to contain Covid, they should be given less emphasis than airborne measures. If an infectious virus is primarily airborne, someone can potentially be infected when they inhale aerosols produced when an infected person exhales, speaks, shouts, sings, or sneezes.
The airborne control measures include ventilation, air filtration, reducing crowding and the amount of time people spend indoors, wearing masks whenever indoors (even if not within 6 feet or 2 metres of others), attention to mask quality and fit, and higher-grade PPE for healthcare and other staff when working in contact with potentially infectious people.
Moreover, transmission rates of Covid is much higher indoors than outdoors, and transmission is greatly reduced by indoor ventilation.
The researchers also cited work demonstrating long-range transmission of the virus between people in adjacent rooms in hotels; people who were never in each other’s presence.
