Even Fine Aerosols Can Spread Influenza Virus

by SP


I appreciate the post by Newsbouy above concerning using masks (and masks covered by a nylon netting to tighten the fit)  to limit spread of respiratory dropplets during influenza epidemics.

A new finding from the University of Maryland was that it is not JUST the large droplets (the kind ejected by coughing and sneezing) that carry the viral particles.  The small droplets that are released by simple breathing also carry virions!  These small droplets to NOT fall to the ground, but drift in air currents potentially traveling down hallways and around corners to other rooms.

Meryl Nass, MD summarizes:

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It is only one study.  But it was carefully done, used interesting methods, and it tried to explore issues that have rarely been studied.  Researchers from the University of Maryland studied students who had new symptoms of influenza to see if infectious flu virus spread during coughs, sneezing, or regular breathing.  They looked at exhaled air during normal breathing.

They found that sneezing is rare during flu and is not important in spread of flu.  They found that cough is not necessary to spread flu:  simply breathing excretes plenty of influenza virus.
This is important because fine aerosols generated simply by breathing remain suspended in air for relatively long periods.  Current thinking is that infectious particles larger than 5 microns fall to the ground quickly, but particles smaller than 5 microns may remain in air longertravel further, and be infectious at larger distances from an infected person.  So staying 3 feet or 6 feet away from a person with flu will not be sufficiently protective.  Typical infection control for flu in healthcare facilities usually involves contact and droplet precautions, for spread over short distances only.
However, this study suggests this may be inadequate, if airborne transmission is a major contributor to spread.  Prevention of airborne (fine aerosol) transmission requires special air handling and the use of negative pressure rooms.  Visitors to the rooms of flu patients will be at risk.

However, even the little surgical masks discussed by Lawrence Wein are uncomfortable for me personally.  They impose an additional resistance to respiration as the user must force air through a mesh creating airflow resistance with every inhalation and exhalation.  For me, this is tiring.  And they fog my glasses.  I am eager to step away from the patient and remove the mask.

At this point in my life, I am fairly healthy, my vitamin D3 levels good and I take N-Acetyl Cysteine and multivitamins and several supplements daily.  I would prefer to JUST GET THE FLU.  To develop antibodies–hopefully without getting too clinically sick.  To work out the TH1 arm of my immune system and develop the memory cells that recognize that virus so that next time I am immune.

If I were chronically ill or had COPD, Diabetes, HIV or were on chemotherapy, then I would stay away from those who are sick.   I might get a Powered Air Purifying Respirator (PAPR) that mounts on the belt and delivers filtered air under pressure to a face mask.  (linked is an inexpensive one.)  This would be my approach to a major pandemic, too.


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