Respiratory infections like flu can be guarded against if people use protective facemasks, according to a study led by British and Aussie scientists.
In their study report, the researcher also say that protective facemasks can even be helpful in defending against a pandemic.
Researchers at Imperial College London and the University of New South Wales, however, have also found that persuading people to wear a mask and to fit it properly is a difficult task, which could limit their effectiveness.
In a clinical trial of the effectiveness of masks, the researchers studied 280 adults from 143 families living in Sydney during the winter flu seasons of 2006 and 2007.
When a child in the household was ill with flu, the volunteers were asked either to wear a mask or not, on a random basis.
The researchers observed that people who wore a mask while their children were sick were four times less likely to become infected by their sick children than non-wearers.
Led researcher Neil Ferguson, director of the MRC Centre for Outbreak Analysis and Modelling at Imperial College, said that the findings suggested that masks could be useful in protecting against flu infections, and could be important in a pandemic.
"In a severe influenza pandemic, there may be limited availability of vaccines in the first few months. In that context, masks are a potentially important additional weapon," Times Online quoted him as saying.
The study, published in the journal Emerging Infectious Diseases, indicates that masks could be an effective extra element of the defence plan, provided that people could be made to wear them consistently.
During the study, fewer than half of those who were asked to wear masks kept them on as directed.