Activities can spread Covid-19 via aerosol particles, study finds

This is how it works: A researcher demonstrating how an aerosol particle collection equipment is used. — Photo from the National University of Singapore

A NEW study by a National University of Singapore (NUS) team has found that an infected person can spread Covid-19 by exhaling fine aerosol particles when breathing, talking and singing, not just though droplets when coughing or sneezing.

The authors of the study on Wednesday said the research findings reinforce the need for infection control measures – such as social distancing, mask-wearing and increased room ventilation – especially in an indoor environment, where airborne transmission of the virus is most likely to occur.

The study, led by researchers from NUS and conducted at the National Centre for Infectious Diseases (NCID), showed that talking and singing can produce two types of viral particles – fine aerosols (less than 5 micrometres in size), and coarse aerosols (larger than 5 micrometres).

The fine aerosols generated from both types of activities contained more viral particles than coarse aerosols, said Professor Paul Tambyah, an infectious diseases expert from the NUS Yong Loo Lin School of Medicine.

Prof Tambyah, a co-author of the paper, said while there was no linear relationship between the size of an aerosol particle and the amount of virus it carries, the size can give researchers a clue as to how much virus or parts of a virus are present in an aerosol particle.

Associate Professor Tham Kwok Wai, from the Department of the Built Environment at the NUS School of Design and Environment, said while previous studies had established the relative amount of aerosols produced through breathing, talking, and singing, none of them measured the amount of Sars-CoV-2 virus particles each activity can to generate.

Prof Tambyah noted that swab samples from two of the 22 patients had such high viral loads that their samples accounted for half the total amount of virus collected in the study.

“This reflects the phenomenon of (virus) dispersal or super spreaders and hopefully the next phase of the study will help us better understand this phenomenon,” Prof Tambyah said.

They are also planning to use the same methods to determine if the aerosol viral load associated with the new variants – especially the Delta variant – is higher than previous strains. — The Straits Times/ANN