The World Health Organization in collaboration with several research institutes have proven that surgical face mask may be effective in preventing symptomatic persons from contracting the COVID-19 virus.
Based on a study conducted by the WHO along with researchers such as the Centre for Infectious Disease Epidemiology and Control, School of Public Health, LKS Faculty of Medicine of Hong Kong (HKUMed) and the University of Maryland.
The study showed that masks reduced the detection of influenza virus in respiratory droplets and seasonal corona viruses in droplets and aerosols.
However, further research is said to be needed in order to determine whether masks can specifically prevent the transmission of SARS-CoV-2, which is closely related to seasonal coronaviruses.
Researchers have previously found out that respiratory viral infections, including those caused by coronaviruses, spread between humans mostly through close contact.
However, there is no direct evidence of how influenza and coronaviruses spread between individuals who are in close proximity – whether by direct contact, large respiratory droplets, or through breathing another person’s exhaled breath. Respiratory viruses can also survive in the environment and potentially spread through indirect contact. Larger respiratory droplets, which fall near the source, as well as aerosols of smaller fine particles can both contain virus and cause short-range transmission. In addition, aerosols can remain in the air for longer and potentially transmit infection over longer distances, particularly if they are generated at higher concentration or if there is little ventilation.
Social distancing, handwashing, ventilation, and the use of face masks, could be important measures to prevent viral transmission. Although the use of face masks has been suggested as a strategy to slow down the transmission of influenza virus, little is known about the relative importance of this strategy in the transmission of other respiratory viruses, including seasonal coronaviruses.
Dr Nancy Leung Hiu-lan, Research Assistant Professor of School of Public Health, HKUMed and the research team recruited 246 people with suspected respiratory viral infections to breathe into a machine — the Gesundheit II — to compare the relative amount of virus in exhaled breath with or without a surgical face mask. The research team provided the same type of surgical mask to all the participants and ensured it was worn correctly.
“In 111 people infected by either coronavirus, influenza virus or rhinovirus, masks reduced detectable virus in respiratory droplets and aerosols for seasonal coronaviruses, and in respiratory droplets for influenza virus. In contrast, masks did not reduce the emission of rhinoviruses.” said Dr Leung.
SARS-CoV-2 and seasonal coronaviruses are closely related and may be of similar particle size. Professor Benjamin Cowling, Division Head of Epidemiology and Biostatistics, School of Public Health, HKUMed, and Co-Director of the WHO Collaborating Centre for Infectious Disease Epidemiology and Control, expressed,
“the ability of surgical masks to reduce seasonal coronavirus in respiratory droplets and aerosols implies that such masks can contribute to slowing the spread of SARS-CoV-2 when worn by infected people.”