SARS-CoV-2 transmission by aerosols: an underestimated question?

Abstract

Dear editor,The actual pandemic caused by SARS-CoV-2 (Severe Acute Respiratory Syndrome), an etiological agent of COVID-19 (Coronavirus Disease 2019), has already infected more than 16 million people in the world, causing about 900,000 deaths in September 2020. The pathogen belongs to a group of microorganisms that infect the lower and upper airways and cause respiratory diseases, from milder forms resembling a common cold, to classic cases of influenza syndrome -with the symptoms of cough, fever, and coryza -to more serious situations, with pneumonia and severe acute respiratory syndrome (SARS) 1 .Initially, it was believed that the transmission of the virus occurred mainly through droplets and contact, considering the transmission by aerosols restricted to specific situations of medical practice such as nebulization, orotracheal intubation, cardiorespiratory resuscitation, and bronchoscopy, among others. More recent studies, however, have shown the importance of aerosol transmission outside the health environment, including reports of virus spread in concerts, elevators, and shopping centers 2 .To understand the dynamics of transmission of SARS-CoV-2 it is necessary to differentiate between droplets and aerosols, two vehicles for the respiratory dissemination of microorganisms that are produced especially by speaking, coughing, or sneezing. The droplets are larger than 5 micrometers. Infection may occur when droplets reach the oral, nasal, and/or ocular mucosa of the susceptible. It is also important to comment that when these droplets are deposited on surfaces, they make transmission by contact possible, from fomites or the surface of a body contaminated by the viral agent, taken later to the mucous membranes 1,3 . In objects made of steel and plastic, the virus