03 Apr 2013

There is very little scientific research on whether wearing surgical face masks can help to reduce the spread of influenza. In view of this, the School of Public Health, The University of Hong Kong Li Ka Shing Faculty of Medicine, in collaboration with the University of Maryland and Harvard School of Public Health have conducted a study on this issue and are the first to report that influenza carriers who wear surgical face masks can reduce the amount of viruses being disseminated into the environment by more than 70%, thus reducing the spread of influenza in the community. This study has recently been published in the international medical journal PLOS Pathogens.

One of the researchers, Dr Ben Cowling, Associate Professor of the School of Public Health, The University of Hong Kong Li Ka Shing Faculty of Medicine says, “This is an important scientific finding which confirms the value of face masks in reducing the spread of influenza. Therefore, we encourage the public to wear surgical face masks when they have influenza so as to protect those around them and reduce the chance of spreading the virus to others.”

Research method and findings

The research was done in the USA in 2009. Researchers used a special device (picture attached below) to measure and assess the amount of exhaled virus in 37 subjects with influenza virus infections, both with and without surgical face masks. The researchers found that surgical face masks can substantially reduce the influenza viruses being disseminated into the environment by more than 70%. In addition, in comparison with larger particles, the study also reported that a much greater number of viruses have been found in tiny particles, with diameter less than 5 microns which can travel long distances through the air. This suggests that tiny particles play an important role in the transmission of influenza.

Background of research

This project was supported by the US Centers for Disease Control and Prevention as part of a series of studies to explore the effectiveness of simple interventions such as face masks and hand washing in reducing the spread of influenza. In order to show if the study results can be applied to Hong Kong, where the conditions are often hotter and more humid than the USA, Dr Ben Cowling is now conducting a similar research project in Hong Kong in collaboration with Hong Kong Baptist Hospital.

About the research team

The study was conducted by the School of Public Health, The University of Hong Kong Li Ka Shing Faculty of Medicine, in collaboration with the University of Maryland and the Harvard School of Public Health in 2009. As for the study at the Hong Kong Baptist Hospital, it is led by Dr Ben Cowling, together with Dr Yen Hui-ling, Assistant Professor of the School of Public Health. The study is financially supported by the Hong Kong Research Grants Council.

To use the press release photo(s) for any publishing, publicity and related purpose, photo courtesy should be given to “Li Ka Shing Faculty of Medicine, The University of Hong Kong”