By Associate Professor Dr. Rafdzah Ahmad Zaki

Why current emphasized is more for the public to practice social distancing rather than wearing a mask? COVID-19 is not an airborne disease. It is spread by tiny droplets released from the nose and mouth of an infected person as they cough or sneeze. Symptomatic people can project the droplets in the air 1-2 meters away when they cough or sneeze. These droplets can land on other people, clothing, and surfaces around them. These droplets also can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs. That is why those with symptoms need to wear a mask, and not to go to a public area.

Social distancing will protect a healthy person by reducing the risk of exposure to the source of infection. Social distancing aims to break the chain of transmissions in the community, thus slow the rate at which the virus is spread in the community, and cases especially critical cases will spread over time. In doing this, health care facilities can cope with the situation, rather than dealing with a high number of cases at once. If all chain of transmissions been broken in the community, this will end the outbreak.

If COVID-19 is not airborne, why the World Health Organization (WHO) is considering "airborne precautions" for medical staff? The WHO only recommends this to medical staff when they perform an aerosol-generating procedure. The medical or hospital environment is not the same as in the public environment. Medical staff dealing with symptomatic patients in a closed environment. Some medical procedure requires very close contact with a patient and some medical procedure also will aerosolised these droplets. Such as when taking nasopharyngeal swabs, performing nebulisation therapy, intubating patient, or manual ventilation with a bag and mask.

For the general public who practising social distancing, they will not be exposed to the droplets that expelled in the air by the symptomatic person. However, hand hygiene still important as the main mode of transmission for COVID-19 is via droplets.

How about those infected but do not show any symptoms (asymptomatic cases)? Not much evidence available on how the asymptomatic person can spread the infection, but studies have shown that asymptomatic person can have a high viral load. Since COVID-19 is not an airborne disease, the asymptomatic person may spread the virus via respiratory droplets. Most likely if the person touches their mouth/nose (mucus or saliva) and touches other objects or very close contact with the asymptomatic person (where the asymptomatic person can exhale their breath directly to the other person). Therefore, practising good hand hygiene is most important here. Social distancing also will keep the general public apart from both symptomatic and asymptomatic cases.

Should I wear a mask if I am healthy or not symptomatic? Face masks (surgical mask) have sold out and been in short supply in many countries. It is important to priorities the use of face mask when it most needed and to those at much higher risk of getting the infection (healthcare worker, enforcement officer, elderly and those with low immune system). The use of masks alone is insufficient to provide an adequate level of protection and other equally relevant measures should be adopted. If masks are to be used, this measure must be combined with hand hygiene and other infection prevention and control measures to prevent the human-to-human transmission (via droplets).

Besides, not all masks can protect us against the virus. A surgical mask may be effective in blocking splashes and large-particle droplets out but does not filter or block very small particles in the air that may be transmitted by coughs, sneezes, or certain medical procedures. Surgical masks also do not provide complete protection from germs and other contaminants because of the loose fit between the surface of the face mask and face. Even if we wear a surgical mask, we still need to keep a distance from COVID-19 patients.

Wearing inappropriate masks might put a person at higher risk as they think they are protected and exposed themselves to the source of infection, but in fact, they are not protected. Practising social distancing will keep people apart from the source of infection.

If we short of supply, I can sew and produce masks using cloths and donate to the healthcare worker. Will this help? The WHO did not recommend the use of cloth masks for healthcare workers under any circumstance, due to the high-risk environment that they are working in. Studies have shown that cloth masks resulted in significantly higher rates of infection than surgical masks. Various types of cloth masks (made of cotton, gauze, and other fibres) have been tested in the past and show lower filtration capacity compared with disposable surgical masks. The physical properties of a cloth mask, and increased moisture retention, may potentially increase the infection risk for healthcare workers. The virus also may survive on the surface of the masks.

The general public can contribute by prioritizing the use of mask, do not delay in seeking medical help if have symptoms, and be honest about travel and contact history to protect others. Maintain social distancing by staying at home and good hand hygiene practice will help fight the spread of COVID-19.

(Associate Professor Dr. Rafdzah Ahmad Zaki is Public Health Medicine Specialist, Universiti Malaya.)