Respiratory Protection for Healthcare Workers in the Workplace Against Novel H1N1 Influenza A A Letter Report (2009) / Chapter Skim
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Letter Report
Letter Report
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and the Occupational Safety and Health Administration (OSHA) the Institute of Medicine convened this committee to provide recommendations regarding the necessary respiratory protection for healthcare workers in their workplace against novel H1N1 influenza A (nH1N1)
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. Panel discussions focused on the current clinical experience with nH1N1, influenza transmission, clinical and community studies on preventing seasonal influenza or other respiratory virus transmission, risks to healthcare workers in various settings, the efficacy and effectiveness 1 of respirators and of medical masks, 2 and decision making in infection control.
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The committee found a paucity of studies comparing the clinical effectiveness of respirators versus medical masks in preventing the transmission of influenza viruses. Several studies are underway or in publication.
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Due to the lack of a strong and conclusive evidence base, the committee concluded that determination of the relative contribution of each route of influenza transmission is essential for long-term preparedness planning. Further, the committee concluded that a stronger evidence base is needed regarding the effectiveness of personal respiratory protection technologies in clinical settings as is the development of improved respiratory protection technologies for healthcare workers.
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P.H., Vice Chair Committee on Respiratory Protection for Healthcare Workers in the Workplace Against Novel H1N1 Influenza A
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are needed to fully protect these frontline workers. This report focuses on the scientific and empirical evidence regarding the efficacy of various types of personal respiratory protective equipment as one measure to protect healthcare workers against nH1N1.
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will conduct a study and issue a letter report to the CDC director and Assistant Secretary for Occupa tional Safety and Health by September 1, 2009. The committee will provide recommendations regarding the necessary respiratory protection, as part of personal protective equipment (PPE)
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including patient placement, personnel restrictions, exposure management, and individual respiratory protection measures of a fit-tested N95 or higherlevel respirator. During its workshop, the committee heard about many potential environmental and administrative controls that could be effective in reducing the number of healthcare workers exposed to nH1N1.
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. These guidelines both recommend the use of hand hygiene, gloves, gowns, and eye protection, but most notably differ in the respiratory protection recommendations.
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1 CDC guidelines recommend that patients with confirmed, probable or suspected cases of nH1N1 who present for care at healthcare facilities be placed into individual rooms with closed doors. 2 Types include EU FFP2 and U.S.
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. The guidelines note an anticipation that only a minority of the patients will need to be cared for at this level, recommending the use of medical masks for direct patient interactions that do not include the potential for procedure-induced aerosol generation.
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Seasonal influenza viruses mutate frequently and this antigenic drift is the reason why vaccine formulations are changed annually. Current seasonal influenza viruses consist of an H1N1 and an H3N2 subtype (subtypes are classified by the surface proteins of the virus called hemagglutinin [H]
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This is particularly the case in determining the overall prevalence of infection and therefore determining the denominator for any calculation of mortality and morbidity rates. Novel H1N1 has emerged as the primary influenza virus in the Southern Hemisphere and in countries such as Australia, certain provinces have reported increased numbers of cases, increased emergency department volume, and increased illness severity (Australian Department of Health and Ageing, 2009)
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In addition, 8 percent of nH1N1-related deaths occurred among persons 65 years and older compared to 90 percent of seasonal influenza-related deaths (National Center for Immunization and Respiratory Diseases, 2009)
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This is in contrast to other seasonal influenza strains that have particularly affected elderly and very young individuals. Younger healthcare workers will be particularly susceptible
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exposure. Because large droplets settle rapidly from air, exposure to droplet spray requires close contact with the influenza patient; for airborne exposure the virus is carried both on smaller respirable 4,5 particles that can penetrate to and deposit in the alveolar region and inhalable particles that deposit in the tracheobronchial and nasopharyngeal airway regions.
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. This letter report is focused solely on airborne exposures that would require respiratory protection.
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TRANSMISSION RISKS FOR HEALTHCARE WORKERS Although much remains to be learned about the routes of nH1N1 transmission and about which medical procedures and types of interactions will result in high-risk exposures to healthcare workers, the virus is known to pose hazards in healthcare facilities and to healthcare workers because of its short incubation period, patient infectivity prior to clinical symptoms, variability of viral shedding among different hosts, multiple routes of transmission, and efficient spread from person to person. While it is widely assumed that aerosol-generating procedures increase the exposure risk to healthcare workers, data about procedural risks are currently lacking.
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experience suggest that healthcare workers are highly motivated to come to work in the face of uncertain risk when they believe that their contributions to patient care are critical and that they will be protected. It is recognized that such actions will not prevent healthcare workers from becoming infected in the community through activities unrelated to their jobs.
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However, because of the loose-fitting design of medical masks (and consequent leakage around the sides) and their lack of protective engineering, medical masks are not considered personal respiratory protective equipment.
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One of the important issues in the discussion of medical masks versus respirators has been the issue of comfort and wearability. A study on worker tolerance for wearing respiratory protective devices over the course of an 8-hour work shift demonstrated that a variety of medical masks and respirators (N95 filtering facepiece, elastomerics, and powered air-purifying respirators)
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The committee did not identify any data from clinical trials comparing the efficacy of N95 respirators to that of N99 or other respirators with superior filtering efficacy and similarly did not find comparisons of respirator protection during various clinical procedures including aerosolgenerating procedures. Some healthcare facilities have used respiratory protection devices with higher levels of protection, such as powered air purifying respirators, during aerosol generating procedures.
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The 2008 IOM study examined studies on the use of respirators and medical masks in preventing respiratory syncytial virus transmission and transmission of SARS (severe acute respiratory syndrome) and found mixed results (IOM, 2008b)
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MacIntyre and colleagues (2009b) conducted a cluster randomized clinical trial to compare the clinical efficacy of medical masks versus N95 respirators with and without fit testing, versus control in influenza transmission in 1,936 healthcare workers in China.
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Clinical effectiveness data are thus quite limited and conflicting at this time, and the committee in its recommendations urges further randomized clinical trials be conducted to explore the types and combinations of PPE that will be effective as one component of strategies to prevent influenza transmission in healthcare workers. FACTORS IN DECISIONS ON RESPIRATORY PROTECTION At its workshop the committee heard several perspectives on decision-making strategies all of which emphasized the importance of focusing on the hierarchy of controls in ensuring a safe work environment.
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• Immunoprophylaxis • Compliance with PPE Work Environment: • Setting (e.g., hospital, emergency medical services, direct care) • Volume of patients • Source control • Ambient conditions • Virus load profile • PPE comfort and wearability • Isolation, cohorting, and other environmental and administrative controls The Patient: • Age • Super-shedder, super-spreader • Underlying health conditions/symptoms • Personal risk factors (e.g., chronic diseases and habits)
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That is, some experts assert that factors including worker compliance may significantly affect the clinical effectiveness of various personal respiratory protection technologies and therefore have implications for appropriate clinical guidelines. The committee found a paucity of studies on the clinical effectiveness of respirators versus medical masks for influenza.
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As noted throughout this report, respiratory protection is one part of a systematic multipronged infection prevention and control strategy. 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.
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Because of the lack of a strong and conclusive evidence base, the committee noted that determination of the relative contribution of each route of transmission is essential for longterm preparedness planning. Secondly, the committee concluded that a stronger evidence base is needed regarding the effectiveness of personal respiratory protection technologies in clinical settings.
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Presentation to the IOM Committee on Respiratory Protection for Healthcare Workers in the Workplace Against Novel H1N1 Influenza A, August 12, 2009. Washington, DC.
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2009. Facemasks and hand hygiene to prevent influenza transmission in households: A randomized trial.
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2008b. Preparing for an influenza pandemic: Personal protec tive equipment for healthcare workers.
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Presentation to the IOM Committee on Respiratory Protection for Healthcare Workers in the Workplace Against Novel H1N1 Influenza A, August 12, 2009. Washington, DC.
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in the southern hemisphere. Presentation to the Committee on Respiratory Protection for Healthcare Workers in the Workplace Against Novel H1N1 Influenza A, August 12, 2009.
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2009b. Interim guidance: Infection prevention and control measures for health care workers in long-term care facilities.
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Infection Control & Hospital Epidemiology 21(11)
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