(April 28, 2009 - Insidermedicine) Wearing a mask over the mouth and nose can provide significant protection against respiratory viruses, including swine flu, according to a study published in Emerging Infectious Diseases.

By way of background, on April 27 the WHO raised its pandemic alert level from 3 to 4 after H1N1 swine influenza A spread from Mexico. By April 28 Mexico had 26 lab confirmed cases and 7 deaths, though 152 deaths out of nearly 2,000 suspected cases have been attributed to the virus. The US had 40 confirmed cases with no deaths, and further cases have been identified in Canada, the UK, Spain, New Zealand, and Israel.

Here is some information about swine flu:

•    It is a respiratory infection that normally only affects pigs but can affect people.

•    Those infected with swine flu can pass it on one day before showing symptoms and continuing on for a week after symptoms disappear.

•    Make sure to wash your hands often, especially after being in public.

Researchers from the University of New South Wales randomly assigned nearly 300 adults to wear a mask or receive no protection whenever a child in their household was sick during the 2006-2007 winter season.

While less than half of the participants assigned to wear a mask actually wore it when they were supposed to, those who did were four times less likely to catch respiratory illnesses, including colds and flu.

Today's research demonstrates how masks may play a crucial role in controlling disease in the case of a pandemic, when medicines and vaccines may be in short supply.

For Insidermedicine in Depth, I'm Dr. Susan Sharma.