New evidence on the transmission of Covid-19 across the world shows that the coronavirus can spread beyond two metres.The study, conducted by scientists at Massachusetts Institute of Technology and the University of Oxford, found that other factors like ventilation, exposure time, crowd size and wearing of face coverings needs to be considered.
Eight out of 10 studies carried out in a recent review showed that horizontal projections of respiratory droplets surpassed the two-metre gauge. One of the studies showed that a droplet spread was detected over six to eight metres.
This suggests that Covid-19 is likely to spread beyond the one-two metre rule in a concentrated atmosphere through coughs or sneezes. Studies conducted on previous outbreaks like Avian flu, MERS-COV and SARS- COV-1 reported spread beyond two metres.
The golden subscribed distance rule is 1 to metres, which is based on a longstanding framework that categorises respiratory droplets into small and large sizes.
The size of a droplet determines how far it can travel from an infected person. In a study, large droplets fall through air quicker than they evaporate and land within 1 to 2 metre range while small droplets which are invisible to the naked eye evaporate quicker than they fall. Without airflow, they remain within the vicinity of the exhale but with airflow, they can spread to greater distances.
Life has gone back to normal in most parts even as Kenya continues to record cases of Covid-19.
This study suggests that as people move and push along the streets, the virus can be transmitted from a person to another.
“Laboratory studies also suggest SARS-CoV-1, SARS-CoV-2, and MERS-CoV viral particles are stable in airborne samples, with SARS-CoV-2 persistent for longest (up to 16 hours),” reads the published report in the BMJ, a medical journal.
UK’s scientific advisory Group for Emergencies (SAGE) estimates 2 to 10 times risk of SARS-COV-2 transmission at one-metre distance compared to two-metre distance.
Review commissioned by World Health Organisation in analysis of distance in relation to Covid-19 transmission shows that less than one metre distance poses a transmission risk of 12.8 per cent compared to 2.6 per cent risk at a distance beyond one metre. But this recommendation fails to account for environmental confounders.
“In the highest risk situations like indoor environments with poor ventilation, high levels of occupancy, prolonged contact time, and no face coverings, such as a crowded bar or night club, physical distancing beyond two metres and minimising occupancy time should be considered,” adds the research study.
Furthermore, “physical distancing should be seen as only one part of a wider public health approach to containing the Covid-19 pandemic. It needs to be implemented alongside combined strategies of people-air-surface-space management, including hand hygiene, cleaning, occupancy and indoor space and air managements and appropriate protective equipment, such as masks, for the setting.”
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