Donning a face mask could help prevent the flu from spreading within households, new research from Australia hints.

Adults who consistently wore a mask after a child living with them came down with respiratory illness were four times more likely to be protected from getting sick themselves than study participants who hadn't been assigned to wear a mask, Dr. Raina McIntyre of the University of New South Wales in Sydney and her colleagues found.

But just 21 percent of the adults in the mask-wearing groups reported using them "often or always" for the amount of time recommended to protect them.

"Wearing a mask is cheap and simple, and should be practical for families," McIntyre told Reuters Health. "It does not require a visit to the doctor or a prescription; families can purchase masks from the pharmacy."

"Some people may find them inconvenient or uncomfortable," McIntyre admitted, "but it's a matter of weighing up the short-term inconvenience of wearing a mask versus the inconvenience of falling sick and having to take time off work."

McIntyre and colleagues studied the effectiveness of face masks for preventing the spread of respiratory illness in 145 men and women aged 16 and older. All were living with a child aged 15 or younger who had recently sought treatment for fever and cough or sore throat.

The adults were randomly assigned to wear a common surgical mask; the more complicated and expensive P2 mask, which includes a respirator and is designed to filter out small particles; or no mask.

Lab tests confirmed respiratory viruses in nearly two-thirds of the children.

Among people who wore the masks as instructed, the risk of getting sick was 74 percent lower compared to the non-mask wearing group. The study was too small to determine if one type of mask was more effective than the other.

But getting people to wear them may be a challenge. On the first day of the study, 38 percent of the adults assigned to wear surgical masks reported wearing them most or all of the time, as did 46 percent of the P2 mask users. But by the fifth day, only 31 percent of the surgical mask group and 25 percent of P2 mask group were wearing them most or all of the time.

The most common reason people cited for not using the mask was discomfort; some said their children didn't want them to wear the mask, while others said they forgot to wear it.

The finding that face masks help curb the spread of flu and other respiratory illnesses within households has implications beyond the home front, especially in the case of an outbreak of serious respiratory illness, McIntyre noted.

"It is important to realise that drugs and vaccines are not necessarily a panacea for infectious disease outbreaks. In some cases, like SARS, there may be no drugs or vaccines at all, and in a pandemic there will almost certainly be delays and shortages in supplies," the researcher said. "As such, we do need to look at the simple, non-pharmaceutical measures such as masks and hand washing that can provide effective protection to people."