Are facemasks effective in preventing H1N1 transmission?

Published in The Hindu on September 5, 2009

mask
CDC has stated in its latest interim recommendation that facemasks are not designed to protect the person from breathing in very small particle aerosols that may contain viruses. — Photo: Wikimedia Commons

Healthy people wearing facemasks was a common sight when the H1N1 virus started infecting people in large numbers in India. But do facemasks really protect a person from getting infected and should people who are not in healthcare setting use them?

The Centres for Disease Control and Prevention (CDC) based in Atlanta, U.S. has stated in its latest interim recommendation that facemasks are not designed to protect the person from breathing in very small particle aerosols that may contain viruses. However, extensive data on their effectiveness to prevent the transmission of H1N1 is currently not available.

Facemask can at most help in stopping droplets from being spread by the person wearing it, and prevent splashes or sprays from reaching the mouth and nose of the person wearing it. The agency also notes that facemasks should be thrown away after a single use.

On the other hand, a respirator (N95), a filter face piece mask, has been designed to protect the person wearing it from breathing in small aerosols that may contain viruses. Being a filter face mask, breathing through a respirator becomes difficult for long periods of time.

The CDC does not recommend the use of N95 for children, despite children falling under the high-risk category.

The CDC notes that the use of facemasks and respirators by healthy people in community and home settings is generally not recommended.

People may choose to wear a respirator when close contact with people with H1N1 infection or influenza-like illness cannot be avoided.

But the use of a respirator alone will not be sufficient. Healthy persons should keep their interactions with an ill person as brief as possible and follow other precautionary measures such as washing hands with soap as frequently as possible and not touch the nose and mouth.

The agency has however been handicapped from assessing the true effectiveness of facemasks and respirators in a community setting. The agency has “extremely limited” information on the effectiveness of these protective gears.

The interim recommendation is therefore been developed based on public health judgement and past experience from using facemasks and respirators in preventing transmission of influenza and respiratory viruses and “on current information on the spread and severity of the novel influenza A (H1N1) virus.”

“The effectiveness of respirators and facemasks in preventing transmission of novel H1N1 (or seasonal influenza) in various settings is not known. Use of a facemask or respirator is likely to be of most benefit if used correctly and consistently when exposed to an ill person,” it notes.

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