September 2009

Pandemic Influenza Alert

Hung Cheung, MD, MPH, FACOEM                         

Sherry Sood, MD, MPH                                                

Dr. Cheung/ OEM Advisor, LLC.

(888) 361-8882

panflu@drcheung-oemadvisor.com

We appreciate the feedback and further questions generated from our last publication on the H1N1 virus. This article will update the current case load from H1N1 as well as outline further practical measures that can be implemented to prevent health, home and business related consequences of H1N1 as flu season approaches. Please feel free to call or email us with any questions or forward the attachment to those who may have questions about H1N1. We will monitor the situation and will have periodic updates for you. They will also be posted on our web site under the “In the News” tab.  We hope this helps as we strive to be your environmental, occupational and public health resource. 

I am thinking of stockpiling face masks at our workplace. How effective are respirators and face masks for protection against H1N1 transmission?

Whenever possible, rather than relying on the use of facemasks or respirators, close contact and crowded conditions should be avoided during an influenza pandemic. Facemasks should be considered for use by individuals who enter crowded settings, both to protect their nose and mouth from other people's coughs and to reduce the wearers' likelihood of coughing on others.  The time spent in crowded settings should be as short as possible. 

Respirators should be considered for use by individuals for whom close contact with an infectious person is unavoidable. This can include selected individuals who must take care of a sick person (e.g., family member with a respiratory infection) at home. Facemasks and respirators should be used in combination with other preventive measures, such as hand hygiene and social distancing, to help reduce the risk for influenza infection during a pandemic. This interim guidance will be updated as new information becomes available.

As far as protective factors, a recent study, which involved close to 2,000 hospital staffers in Beijing, showed that N95 respirators reduced the risk of respiratory illness by a significant 60% and the risk of confirmed influenza by 75%, whereas surgical masks had no effect. The study was reported at this month’s American Society for Microbiology meeting in San Francisco but has not yet been published in full form. It is described as the first randomized controlled trial comparing the effectiveness of N95 respirators and surgical masks. N95 respirators are designed to fit closely to the face and filter out 95% of airborne particles, whereas surgical masks are looser fitting and were originally designed to prevent the wearer from infecting others. Note: respirators should be properly fitted and new CDC recommendations on respirator usage will likely be published soon.