Respiratory virus shedding in exhaled breath and efficacy of face masks

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We identified seasonal human coronaviruses, influenza viruses and rhinoviruses in exhaled breath and coughs of children and adults with acute respiratory illness. Surgical face masks significantly reduced detection of influenza virus RNA in respiratory droplets and coronavirus RNA in aerosols, with a trend toward reduced detection of coronavirus RNA in respiratory droplets. Our results indicate that surgical face masks could prevent transmission of human coronaviruses and influenza viruses from symptomatic individuals.




Mikael Nordfors's picture

"Our findings indicate that surgical masks can efficaciously reduce the emission of influenza virus particles into the environment in respiratory droplets, but not in aerosols12. Both the previous and current study used a bioaerosol collecting device, the Gesundheit-II (G-II)12,15,19, to capture exhaled breath particles and differentiated them into two size fractions, where exhaled breath coarse particles >5μm (respiratory droplets) were collected by impaction with a 5-μm slit inertial Teflon impactor and the remaining fine particles 5 μm (aerosols) were collected by condensation in buffer. We also demonstrated the efficacy of surgical masks to reduce coronavirus detection and viral copies in large respiratory droplets and in aerosols (Table 1b). This has important implications for control of COVID-19, suggesting that surgical face masks could be used by ill people to reduce onward transmission. "

This means that there could be a reduction, but not an elimination of contagion from sick people. This does not implicate that wearing face masks can:

1. Protect non-infected people to get the infection by wearing face masks.

2. Reduce Contagion by non-symptomatic individuals, as their is no proven such contagion.

The conclusion is: If you have symptoms of infection, you might diminish, but not prevent others from getting your infection by wearing a face mask.