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www.thevillagenews.co.za
15 July 2020
MY WELLNESS
Airborne transmission of Covid-19
W
ith ongoing research around the world on the novel Coronavirus that causes Covid-19, new evidence keeps coming to light about how the virus is transmitted, how it affects those who are infected, how best to treat the disease, and what long-term damage is suffered by those who do recover. Perhaps the most important of these is the aspect of transmission – and understanding exactly how people are becoming infected with Covid-19 – as this would inform decisions made in the everyday lives of people that could help prevent infections. Although little was known about this particular virus when it first started spreading around the globe at the beginning of the year, word from the World Health Organisation (WHO) was that Covid-19 is a respiratory disease that is primarily spread by small droplets through person-to-person contact. These respiratory droplets were
heavy enough to fall to the floor pretty quickly, the WHO said, which meant that transmission could only occur if an infected person sneezed or coughed close to you, or if you touched a contaminated surface and transferred the virus by touching your face. This is what all the hand-washing, mask-wearing and social distancing recommendations were based on. So far, so good – and those three things remain the most important safety precautions that should be practised by everyone. However, scientists were baffled by the many examples of outbreaks that were occurring in specific settings, such as hospitals, churches, offices, conference centres, casinos, restaurants and bars. What was it about these venues that turned them into so-called ‘super-spreaders’ of the disease, even among people who had not been in direct contact but were in fact halfway across the room from an
infectious person? Recently, 239 scientists from 32 countries presented a growing body of evidence to the WHO that Covid-19 can be spread through airborne transmission. This means that the virus is not only present in droplets but also in aerosols, which are much smaller and can float in the air over several metres. This has led the WHO to issue a new scientific brief on coronavirus transmission last week. "There have been reported outbreaks of Covid-19 reported in some closed settings, such as restaurants, nightclubs, places of worship or places of work where people may be shouting, talking, or singing," the WHO states in its new guidelines. "In these outbreaks, aerosol transmission, particularly in these indoor locations where there are crowded and inadequately ventilated spaces where infected persons spend long periods of time with others, cannot be ruled out."
University of the Witwatersrand Professor Shabir Madhi told eNCA last week that airborne transmission of Covid-19 is a reality and has been underestimated. He said previously the focus was around the notion that patients are infected when coming into contact with contaminated surfaces, but that has since changed. “Unfortunately, more recently, based on a number of experiences, what we term as super-spreader events suggest there is a fair amount of airborne transmission taking place. “There are two parts to it, but the part we are referring to now is extremely small micro-droplets that are suspended in the air for a reasonable period of time. People who are in that vicinity, especially when the area is poorly ventilated, might inhale those contaminated micro-droplets and that could cause an infection,” Madhi said. He warned that it is now more import-
ant than ever for everyone to wear masks, especially in an indoor space with poor airflow, as micro-droplets pose a risk of exposure beyond 1 to 2 metres by an infected person. The recommended measures to mitigate airborne transmission include avoiding crowded spaces and providing sufficient and effective ventilation (open windows to let in outdoor air, minimise recirculating air) particularly in public buildings, public transport, workplace environments, schools, hospitals, and care homes for the elderly. Although it is winter now and the weather might not always allow for it, we should all keep in mind that being outside carries less risk than being in an indoor space with other people. - Hedda Mittner SOURCES: timeslive.co.za, businessinsider.co.za, neurosciencenews.com
