The COVID-19 virus which has wreaked havoc in the recent days belongs to the large family of Corona viruses. The COVID -19 viruses cause respiratory diseases in animals and humans, ranging from common flu to serious respiratory ailments like Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS).
Two types of droplets
The respiratory diseases, in general, are transmitted through two types of droplets- the respiratory droplets which have a diameter larger than ( >) 5-10 micrometers, and the droplet nuclei which have a diameter smaller than (<) 5 micrometers. According to the WHO, COVID-19 is primarily transmitted via the respiratory droplets (droplet transmission) and contact routes.
Droplet transmission occurs when a person comes in contact with an infected person’s mucosae or conjunctiva. This can spread via direct contact within 1 meter of distance or indirect contact in which healthy people come in contact with infected surfaces touched by the infected person or when medical instruments used for the treatment of infected persons are used on a healthy person.
Now, Airborne transmission and droplet transmission are different from each other. In Airborne transmission, droplet nuclei are the agents of transmission that have diameters less than (<) 5 micrometers which can persist in the air for a longer time and be transmitted to others over distances greater than 1 m. So, WHO has been informing to date that this virus is not airborne, but is transmitted through larger droplets and physical contact.
Rules and recommendations
On 4th July, Saturday, the New York Times reported that 239 scientists from 32 countries say that,COVI-19 can also be transmitted through smaller particles (droplet nuclei) and infect a huge number of people. There has been a need for WHO to revise its rules and recommendations according to the new evident discovery. As mentioned above, the WHO had clearly stated that the COVID-19 virus can be contracted via infected droplets from mouth and nose, let out while sneezing, coughing, or speaking.
The scientists are planning to publish an open letter to the agency in a scientific journal this week, showing the evidence for the transmission of the virus through smaller particles. They say that “whether carried by large droplets that zoom through the air after a sneeze, or by much smaller exhaled droplets that may glide the length of a room, the corona virus is borne through the air and can infect people when inhaled”.
However, Dr. Benedetta Allegranzi, the WHO’s technical lead of infection prevention and control, said that “especially in the last couple of months, we have been stating several times that we consider airborne transmission as possible but certainly not supported by solid or even clear evidence.” So, WHO is of the opinion that, the pieces of evidence are still not enough to announce the conjecture as credible.
Regardless of the size of droplets that transmit the virus or the period of their persistence in the air, all of us need to take necessary precautions to be safe and keep others safe. We need to wear a mask whenever we go outside, use sanitizer, avoid crowded places, practice social distancing, avoid touching our eyes, nose or mouth, and most importantly, practice sneezing and coughing into a flexed elbow.