The COVID-19 may travel in aerosols


The new coronavirus appears to linger in the air in crowded spaces or rooms that lack ventilation. That COVID-19 can spread through tiny airborne particles known as aerosols. People produce two types of droplets when they breathe, cough or talk.
Larger ones drop to the ground before they evaporate, causing contamination mostly via the objects on which they settle. Smaller ones those that make up aerosols can hang in the air for hours. The concept of aerosol transmission is developed to resolve limitations in conventional definition of airborne and droplet transmission. Aerosol transmission is biologically plausible when infectious aerosols are generated by or from an infectious person, the pathogen remain viable in the environment for some period of time, and the target tissue in which the pathogen intiates infection are accessible to the aerosol. The notion of viral particles hanging in the air, ready to infect passersby, may seem scary, but to become an aerosol, droplets containing viral particles must first be transformed into a light mist, thin enough to be supported by the air.
By definition, aerosols are less than 0.0002 inches (5 microns) in diameter while typical respiratory droplets exceed this size. But tiny airborne aerosols could travel farther than the 6 feet now recommended in most social distancing advisories. In fact,”the maximum transmission distance of [coronavirus] aerosol might be 4 meters (13feet). The potential for this virus to spread via aersols is particularly scary,because its essentially a hybrid between an airborne and a droplet virus, and that the droplets are able to hang out in the air for an extensive period of time and potentially infect other people.”
Biological plausibility of aerosol transmission is evaluated for severe Acute Respiratory Syndrome (SARS) and also discussed for Mycobacterium tuberculosis, influenza, and Ebola virus.
Respiratory infections can be transmitted through droplets of different sizes: when the droplet particles are >5-10micrometers in the diameter they are referred to as respiratory droplets, and when then then are <5micrometers in the diameter, they are referred to as droplet nuclei.
According to current evidence, COVID-19 virus is primarily transmitted between people through respiratory droplets and contact routes. In the context of COVID-19, airborne transmission may be possible in specific circumstances and settings in which procedures or support treatments that generate aerosols are performed i.e., endotracheal intubation, bronchoscopy, open suctioning, administration of nebulized treatment, manual ventilation before intubation, turning the patient to the prone position, disconnecting the patient from the ventilator, non-invasive positive-pressure ventilation, tracheostomy, and cardiopulmonary. Aerosols, by contrast, can potentially travel across far greater distances; the virus that causes chickenpox, for example, can travel tens of yards from an infected person and incite secondary infections elsewhere in the environment, and can remain in an area even after the person who emitted them has left. However, in the current study, the researchers did not examine how far SARS-CoV-2 could conceivably travel through the air.
There is some evidence that COVID-19 infection may lead to intestinal infection and be present in faeces. However, to-date only one study has cultured the COVID-19 virus from a single stool specimen. There have been no reports of faecal oral transmission of the COVID-19 virus to-date.
The findings affirm the guidance from public health professionals to use precautions similar to those for influenza and other respiratory viruses to prevent the spread of SARS-CoV-2: (1) Avoid close contact with people who are sick; (2) Avoid touching your eyes, nose, and mouth; (3) Stay home when you are sick; (4) Cover your cough or sneeze with a tissue, then throw the tissue in the trash; (5) Clean and disinfect frequently touched objects and surfaces using a regular household cleaning spray or wipe.
WHO continues to recommended droplet and contact precaution for those people caring for COVID-19 patients. WHO continues to recommended air borne precautions for circumstances and settings in which aerosol generating procedures and support treatment are performed, according to risk assessment. These recommendations are consistent with other national and international guidelines, including those developed by the European Society of Intensive Care Medicine and Society of Critical Care Medicine and those currently used in Australia, Canada, and United Kingdom.
At the same time, other countries and organizations, including the US Centres for Diseases Control and Prevention and the European Centre for Disease Prevention and Control, recommended airborne precautions for any situation involving the care of COVID-19 patients, and consider the use of medical masks as an acceptable option in case of shortage of respirators (N95, FFP2 or FFP3). Current WHO recommendations emphasize the importance of rational and appropriate use of all PPE, not only masks, which requires correct and rigorous behavior from healthcare workers, particularly in doffing procedures and hand hygiene practices. WHO also recommends staff training on these recommendations, as well as the adequate procurement and availability of the necessary PPE and other supplies and facilities.
Finally, WHO continues the emphasize the utmost importance of frequent hand hygiene, respiratory etiquette, and environmental cleaning and disinfection, as well as the importance of maintaining physical distances and avoidance of close, unprotected contact with people with fever or respiratory symptoms.