Claiming that there's evidence for such spread, the scientists have asked the World Health Organization (WHO) to revise recommendations, the New York Times reported on Saturday. "We do not know that for COVID", Tellier said. "We just need to pay more attention to these efforts and to give them equal weight as handwashing".
Understanding how COVID-19 is transmitted from one person to the next enables us to design effective public health interventions to minimise the risk of transmission.
The rate of both new virus infections and deaths are rising at the fastest pace in three months, as officials lift a vast lockdown of India's 1.3 billion people that has left tens of thousands without work and shuttered businesses.
First, an infected person releases the droplets via a cough or a sneeze, and they are inhaled by a healthy person.
Thanks to gravity, these large droplets don't generally travel far before landing.
The authors of the new commentary recognized that the evidence for microdroplet transmission was "admittedly incomplete", but argued that the evidence for large droplets and surface transmission was also incomplete yet still formed the basis for health guidelines. "The big unknown is how much infection does it cause, and what can other measures like managing airflow differently, UV light exposure, etc. reduce it over wearing a mask, handwashing and physical distancing".
"The airborne transmission word seems to be loaded", Milton, one of two main authors of the letter, told CNN.
Covid-19: Hundreds of scientists say coronavirus is airborne
A staggering 212,326 people were diagnosed worldwide with COVID-19 on July 4, 2020, according to the World Health Organisation . Allegranzi said that airborne transmission "would have resulted in many more cases and even more rapid spread of the virus".
"Hand washing and social distancing are appropriate, but in our view, insufficient to provide protection from virus-carrying respiratory microdroplets released into the air by infected people". These droplets are less than 5 micrometres in size and generally called aerosols.
Perhaps the strongest evidence, however, comes through the various case reports of superspreading events.
One notable early example was from a choir practice in the United States where nearly 50 people were infected even though they maintained physical distance. A loud bar, where people must raise their voices to be heard, is a flawless storm of close contact, poor air circulation and people generating a lot of virus-carrying particles by talking, laughing and shouting. Rather than think of airborne transmission as a simple yes or no, it should be considered a spectrum.
The WHO was relying on a dated definition of airborne transmission. People produce thousands of these droplet nuclei per second while talking and the aerosolized particles can contain live viruses and float in the air for hours.
Good ventilation could lower the risk of airborne transmission in indoor spaces.
Foreign students must leave the United States if their school's classes this autumn will be taught completely online or transfer to another school with in-person instruction, the U.S. Immigration and Customs Enforcement (ICE) agency announced.
On the other hand, if this airborne transmission is a significant issue, safety guidelines could become much, much stricter.
The CDC, meanwhile, has stated that the coronavirus touching infected surfaces is not the primary way the virus spreads. For this reason, the World Health Organization has emphasized hand-washing even as the US Centers for Disease Control and Prevention now downplays the likelihood of picking up the virus from contaminated surfaces.