Respiratory virus shedding in exhaled breath and efficacy of face masks

Abstract

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.Respiratory virus infections cause a broad and overlapping spectrum of symptoms collectively referred to as acute respiratory virus illnesses (ARIs) or more commonly the 'common cold' . Although mostly mild, these ARIs can sometimes cause severe disease and death 1 . These viruses spread between humans through direct or indirect contact, respiratory droplets (including larger droplets that fall rapidly near the source as well as coarse aerosols with aerodynamic diameter >5 µm) and fine-particle aerosols (droplets and droplet nuclei with aerodynamic diameter ≤5 µm) 2,3 . Although hand hygiene and use of face masks, primarily targeting contact and respiratory droplet transmission, have been suggested as important mitigation strategies against influenza virus transmission 4 , little is known about the relative importance of these modes in the transmission of other common respiratory viruses 2,3,5 . Uncertainties similarly apply to the modes of transmission of 7 ).Some health authorities recommend that masks be worn by ill individuals to prevent onward transmission (source control) 4,8 . Surgical face masks were originally introduced to protect patients from wound infection and contamination from surgeons (the wearer) during surgical procedures, and were later adopted to protect healthcare workers against acquiring infection from their patients. However, most of the existing evidence on the filtering efficacy of face masks and respirators comes from in vitro experiments with nonbiological particles 9,10 , which may not be generalizable to infectious respiratory virus droplets. There is little information on the efficacy of face masks in filtering respiratory viruses and reducing viral release from an individual with respiratory infections 8 , and most research has focused on influenza 11,12 .Here we aimed to explore the importance of respiratory droplet and aerosol routes of transmission with a particular focus on coronaviruses, influenza viruses and rhinoviruses, by quantifying the amount of respiratory virus in exhaled breath of participants with medically attended ARIs and determining the potential efficacy of surgical face masks to prevent respiratory virus transmission.

Efficacy of face mask in preventing respiratory virus transmission: a systematic review and meta-analysis

“…The physical characteristics of the mask can prevent the respiratory tract from contacting the outside virus, thereby reducing the risk of infection with respiratory diseases. The latest research by Leung et al found that surgical masks significantly reduced the detection of influenza virus RNA in respiratory droplets and coronavirus RNA in aerosols, and there was a tendency to reduce coronavirus RNA in respiratory droplets [36]. Our study shows that masks worn by non-infected people can effectively prevent the spread of respiratory viruses and reduce the overall risk of respiratory virus infection by 65%.…”

The Potential role of Particulate Matter in the Spreading of COVID-19 in Northern Italy: First Evidence-based Research Hypotheses

“…Further experimental studies could confirm the possibility that particulate matter may act as a "carrier" for the viral droplet nuclei, impressing a boost effect for the spreading of the viral infection, as it has been shown for other viruses. Recent studies [36] and recommendation [37] about increased social distancing indicate that a recommended interpersonal distance of significantly more than one meter and usage of personal masks [38] are advisable prevention measures.…”

Epidemic prevention and control measures in China significantly curbed the epidemic of COVID-19 and influenza

“…The face masks were common sight during the influenza epidemic period, but the role in preventing influenza virus transmission remains questionable 18 . Recently, Leung NHL et al's research indicates that surgical face masks could prevent transmission of COVID-19 and influenza virus from symptomatic individuals 19 . Whether these measures play an important role in controlling COVID-19 and influenza need further research.…”