N95 respirators to Protect workers From AH1N1

To help protect against respiratory infection, healthcare workers who interact with patients suspected or confirmed of being infected with the novel pandemic influenza A strain H1N1 should wear fitted N95 respirators, which filter better than looser medical masks, according to a letter report released September 3 by the Institute of Medicine (IOM).

"Based on what we currently know about influenza, well-fitted N95 respirators offer healthcare workers the best protection against inhalation of viral particles," committee chair Kenneth Shine, executive vice chancellor for health affairs at the University of Texas System in Austin, and former IOM president, said in a news release. "But there is a lot we still don't know about these viruses, and it would be a mistake for anyone to rely on respirators alone as some sort of magic shield. Healthcare organizations and their employees should establish and practice a number of strategies to guard against infection, such as innovative triage processes, handwashing, disinfection, gloves, vaccination, and antiviral drug use."

Although the IOM letter endorses the current US Centers for Disease Control and Prevention (CDC) recommendation for respiratory protection against H1N1, it emphasizes that the use of N95 respirators should be only 1 element of a comprehensive program of workers' and healthcare organizations' infection-control strategies. If the prevalence of clinically apparent H1N1 infection increases during this fall influenza season, it will be vitally important to protect healthcare workers from infection. In light of their central role in treating patients, such measures could reduce the overall impact of this pandemic.

Even with the best available scientific evidence to date, the extent of airborne transmission of H1N1 is unknown. It is also unclear whether physical contact with contaminated fluids or surfaces is needed for infection to occur. The letter therefore recommends increased research to address these unanswered questions and to design and develop better protective equipment to improve the comfort, safety, and job performance of healthcare workers.

However, studies suggest that inhalation of airborne viruses is a probable route of influenza infection, supporting the use of respiratory protection during an outbreak. Because the IOM was specifically charged with evaluating personal protective equipment designed to reduce the risk for respiratory infection, the committee focused on studying the efficacy of medical masks and respirators.

N95 respirators and medical masks are similar in appearance and both cover the nose and mouth. Medical masks fit loosely over the face, whereas respirators are designed to form a tight seal against the wearer's skin. When properly fitted and worn as recommended, N95 respirators filter out at least 95% of particles 0.3 μm or larger, which is a threshold smaller than the influenza virus particle.

Because of the limited scope and time frame in which develop this report, the IOM committee did not address how to implement their recommendations, did not determine likely costs and needed supplies, and did not evaluate the effects of vaccination, prophylactic use of antiviral drugs, or other infection-control measures. To reduce the probability that healthcare workers will be exposed to and infected by H1N1, the committee stressed the importance of using a variety of infection-control strategies.

Specific recommendations of the IOM committee regarding the use of respirators by healthcare workers are as follows:

Healthcare workers, including those in nonhospital settings, who are in close contact with patients who have novel H1N1 influenza or influenza-like illnesses should use fit-tested N95 respirators or respirators that are demonstrably more effective. This should not be a stand-alone solution, but a single measure in the continuum of safety and infection-control efforts to decrease the risk for infection.
The IOM committee endorses the current CDC guidelines and recommends continuing to follow them until or unless additional evidence shows that other forms of protection or other guidelines are equally or more effective.
Employers should ensure that the use and fit testing of N95 respirators is in accordance with Occupational Safety and Health Administration (OSHA) regulations. Furthermore, healthcare workers should use these respirators in accordance with regulations and employer policies.
The committee does not recommend the use of N95 respirators for all healthcare workers, only for those in initial contact with patients presenting with undetermined febrile respiratory illnesses and those in close contact with individuals with confirmed or suspected novel H1N1 influenza.
Evidence is insufficient at this time to completely define close contact for all settings and situations. However, close contact has generally been defined as being within 6 feet of a patient. The entrance of a healthcare worker into an enclosed space with a patient, such as in an isolation room, has been shown to increase the worker's risk for infection.
Specific recommendations of the IOM committee regarding the need to increase research on influenza transmission and personal respiratory protection are as follows:

Further research is needed to resolve unanswered questions about the relative contribution of different routes of influenza transmission.
Randomized clinical trials should test the efficacy of personal respiratory protection technologies in a variety of clinical settings.
The next generation of personal respiratory-protection technologies for healthcare workers should be designed and developed to enhance safety, comfort, and ability to perform work-related tasks.
"As noted throughout this report, respiratory protection is 1 part of a systematic multipronged infection prevention and control strategy," the authors conclude. "The goal is to minimize risk and decrease the number of healthcare workers with potential exposure to undetermined febrile respiratory illnesses and to accurately and rapidly diagnose patients who necessitate antivirals, antimicrobials, and other essential medical and public-health interventions."

The CDC and OSHA requested and supported this study. They note that any opinions, findings, conclusions, or recommendations expressed in the letter are those of the author(s) and do not necessarily reflect the view of the supporting organizations or agencies.

Institute of Medicine. September 3, 2009. Respiratory protection for healthcare workers in the workplace against novel H1N1 influenza A: A letter report. Washington, DC: The National Academies Press.

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Authors and Disclosures
Journalist
Laurie Barclay, MD
freelance writer and reviewer, MedscapeCME

Disclosure: Laurie Barclay, MD, has disclosed no relevant financial relationships.

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