This year, health experts around the world have revised their views on the spread of the coronavirus. Aerosol scientists, virologists and other researchers had determined in 2020 that the virus was spreading through the air, but it took until 2021 for major public health agencies to acknowledge the fact. Admission could have broad implications for everything from public health recommendations and building codes to marching band practices (SN: 08/14/21, p. 24).
For decades, doctors and many researchers thought that respiratory viruses such as cold and flu viruses were spread primarily by people touching surfaces contaminated with mucus droplets and then touching their face. That’s why, at the start of the pandemic, disinfectant wipes flew off store shelves.
Surface-to-face transfer is still a likely route of infection for some cold-causing viruses, such as respiratory syncytial virus, or RSV. But it turns out that the coronavirus spreads mainly through fine aerosol particles that can stay in the air for hours, especially indoors.
People spread these aerosols by coughing or sneezing, but also by talking, singing, shouting and even breathing quietly, allowing infected people to spread the disease before they even know they are sick. Some evidence suggests that the coronavirus may be evolving to spread more easily through the air (SN: 09/25/21, p. 6).
It took tons of data and more than 200 scientists to push the World Health Organization and other public health agencies to acknowledge the airborne spread of the coronavirus. In April 2021, WHO and the US Centers for Disease Control and Prevention updated their recommendations to note that airborne spread is a major route of infection (SN online: 05/18/21).
This recognition was essential for the public to understand why the wearing of well-fitting masks is necessary in indoor public places (SN: 3/13/21, p. 14; SN online: 07/27/21). Masking, social distancing and other protective measures against the coronavirus are also credited with nearly wiping out the flu last winter (SN online: 02/02/21). Experts fear a resurgence of colds and flu this winter if these measures are not maintained (SN online: 8/12/21).
The knowledge that COVID-19 is an airborne disease has led to measures such as rearranging seats in orchestras (SN online: 06/23/21) and updated recommendations for good ventilation and filtration in buildings. Some scientists and activists have also suggested that indoor air safety should be regulated to reduce the spread of disease, as should food and drinking water safety standards.