Wednesday, October 25, 2006

Face-off against flu

As some of us line up for flu shots this fall, experts consider what could be the most serious future threat to public health: an emerging strain of influenza similar to the virus that killed tens of millions worldwide in 1918.

If history repeats itself and a virulent influenza virus spreads across the globe, what specific steps should individuals take to protect themselves? An opinion piece in today's New York Times offers a matter-of-fact approach to this worrisome scenario.

Dr. Lawrence M. Wein, of Stanford University, writes that while the experts encourage non-pharmaceutical efforts such as frequent hand-washing, there's no consensus on how the flu virus is most likely to be transmitted.

Viruses spread through a community in three ways:
- Droplet transmission, in which a contagious person sneezes or coughs directly into the face of a susceptible individual;
- Contact transmission, when the virus passes either hand-to-hand or indirectly via a doorknob or telephone;
- Aerosol transmission, in which an uninfected person inhales evaporated virus particles.

Even the U.S. government’s Pandemic Influenza Plan states “the relative clinical importance of each of these modes of transmission is not known.”

Wein and a Stanford graduate student, Michael Atkinson, looked at data on influenza and rhinovirus, the culprit behind the common cold. They determined that flu is most commonly passed along as an aerosol, and hand-washing would make little difference.

“Face protection would guard against aerosol and droplet transmission, and even reduce contact transmission by making it difficult to place fingers in one’s mouth or nose,” says Wein.

He was surprised to find that simple surgical masks did a pretty good job of blocking virus particles, performing almost as well as the type of respirators worn by construction workers.

In hospitals, these masks are discarded after a single use, but an environmentally minded citizen could recycle: the virus would not survive on the surface of a mask for more than a few hours, after which the mask could be re-used.

“The government and the public health community must switch mindsets, from the current perspective of protecting workers paid to do a dangerous job every day, to that of providing citizens with the tools to best protect themselves during a pandemic. It may take 18 months to build a stockpile of respirators and masks, so there is no time to lose,” Wein concludes.

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