Airborne transmission of the new coronavirus is a hot topic this week, with 239 scientists urging the World Health Organization to recognize the importance of aerosols in THE spread of COVID-19,media BGR reported. WHO said earlier this week that emerging evidence did support aerosol transmission and announced that it would issue updated guidelines. On Friday, the organization released a new COVID-19 transmission guidelines, which do address the risks of airborne transmission, but say that droplet seistransmission and human contact are the main forms of infection only under certain conditions.
The updated scientific brief, published on the WHO website on 10 pages, details the spread of the SARS-CoV-2 virus and its “impact on infection prevention measures”.
“Airborne is defined as the spread of infectious pathogens caused by the presence of droplet nuclei (aerosols) suspended in the air for long distances and for long periods of time.” The paper says in a section devoted to air borne. However, WHO has made it clear that aerosol transmission can only occur in certain circumstances. “”The air bornes of SARS-CoV-2 may occur in medical operations that produce aerosols (“aerosol production operations”). WHO and the scientific community have been actively discussing and assessing whether SARS-CoV-2 can also be transmitted through aerosols without aerosol operation, especially in poorly ventilated indoor environments.
WHO linked to experiments to prove that aerosol transmission is possible, but noted that “more research is needed in view of the possible impact of this route of transmission”. This means that WHO will not issue mandatory mask regulations and will not require ventilation policies for the indoor environment to reduce the risk of transmission. Nevertheless, air borne-in-the-line points were given to the main points of the briefing, indicating that WHO was taking the matter seriously.
The air borne-out of the virus can occur in a health-care environment, where specific medical operations, called aerosol-producing operations, produce very small droplets called aerosols. Some outbreaks related to indoor crowded spaces have been reported, for example, in choir exercises, restaurants or fitness classes, where aerosol transmission can occur and spread in conjunction with droplets.
WHO also says that masks should be recommended under certain conditions and does not say that they should be worn at all times.
Given that asymptomatic infections can also transmit the virus, it is prudent to encourage the use of fabric masks in public places where community transmission is present and other preventive measures, such as physical isolation, are not possible. Fabric masks, when made and worn properly, can act as a way to prevent droplets from being discharged from the wearer into the air and the environment. However, masks must be used as part of comprehensive preventive measures, including regular hand hygiene, physical distance where possible, respiratory protocol, environmental cleanliness and disinfection. Recommended precautions also include avoiding crowded gatherings indoors, especially when the physical distance is far.
WHO explains that people with symptoms are mainly infected through droplets and close contact. The WHO says asymptomatic carriers and patients before asymptomatic can also spread the virus.
The document also recognizes that the issue of dissemination still exists and needs to be addressed:
There are still many unanswered questions about the spread of SARS-CoV-2, and research to find answers to these questions is under way and encouraged. Current evidence suggests that SARS-CoV-2 is transmitted from person to person primarily through respiratory droplets and contact channels — although aerosols in medical settings where aerosols are programmed to develop procedures are another possible mode of transmission – the spread of COVID-19 is in close contact with others in the pre-symptom or symptomatic period with others without proper personal protective equipment (direct physical or face-to-face contact with suspected or confirmed cases within a distance of one meter, and for a longer time) and happen. Infected persons can also spread without symptoms, but the extent of this transmission is not entirely clear and further research is urgently needed. The role and extent of airborne transmission needs further study outside medical institutions, especially in poorly ventilated close-up environments.
Dr. Donald Milton, an air biologist at the University of Maryland and lead author of an open letter to 239 scientists, told NPR that his WHO briefing “feels complicated.” I’m glad to see that they’ve changed a little bit,” he said. “But I’m disappointed that they didn’t take any further action.”