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The debate over the best respiratory protection for healthcare workers against H1N1 influenza continues, leaving clinicians eager to comply but caught between the guidance issued by government agencies, the data from various researchers, and the recommendations from infectious diseases and infection control associations.
A study which suggested that N95 respirators offered better protection against the H1N1 influenza virus than surgical face masks was called into question at the annual meeting of the Infectious Diseases Society of America (IDSA) in October.
The paper was written by Raina MacIntyre, PhD, a professor of infectious diseases epidemiology and the head of the University of New South Wales School of Public Health and Community Medicine, in Sydney, Australia. MacIntyre and her colleagues tracked healthcare workers in Beijing, China, who wore surgical face masks and N95 respirators, and compared rates of influenza and respiratory illness. Preliminary findings were presented at a meeting of the Interscience Conference on Antimicrobial Agents and Chemotherapy in September. MacIntyre says the research has not been retracted, but that the same data had been analyzed differently for the final paper; in essence, researchers excluded a control group of almost 500 healthcare workers and adjusted the statistics, and they maintain that the difference in infection rates between mask and respirator use was not statistically significant. At the time of writing, McIntyre’s research has not yet been published in a journal.
Proponents of surgical face masks say they are less expensive and easier to wear than N95 respirators; but scientifically, there is evidence indicating the effectiveness of each type of protective apparel. In a randomized trial designed to study surgical masks vs. N95 respirators for preventing influenza transmission, Loeb et al. (2009) conducted a randomized controlled trial of 446 nurses in emergency departments, medical units and pediatric units in eight tertiary-care hospitals. Nurses wore either a fit-tested N95 respirator or a surgical mask when providing care to patients with febrile respiratory illness during the 2008-2009 influenza season; 225 nurses received surgical face masks and 221 received N95 respirators. Influenza infection occurred in 50 nurses (23.6 percent) in the surgical face mask group and in 48 (22.9 percent) in the N95 respirator group. The researchers concluded that there was no difference in influenza rates among nurses using one type of protective device versus the other.
Srinivasan and Perl (2009) point out that “the Centers for Disease Control and Prevention (CDC) guidelines for preventing transmission of seasonal influenza are intended to limit exposure to large respiratory droplets and recommend the use of a medical (surgical) mask during the care of a patient with influenza as part of a comprehensive infection control strategy. However, data suggest that under certain conditions, influenza viruses can be transmitted via smaller particles that evade filtration by such masks. Unlike medical masks, N95 particulate respirators protect wearers from small particles when appropriately designed and worn. Recommendations to prevent influenza transmission take on special importance during pandemics, when there is little, if any, native immunity and vaccine is not available immediately.”
There is dispute in the infectious disease community regarding the exact transmission of the H1N1 influenza virus, which is at the core of the respiratory protection debate. Mark E, Rupp, MD, president of the Society for Healthcare Epidemiologists of America (SHEA) and professor of infectious diseases at the University of Nebraska Medical Center, says that current recommendations for respiratory protection are overkill for the level of protection needed against influenza droplets.
In June, SHEA issued the following statement: “At the start of the 2009 outbreak, there was uncertainty regarding the transmission dynamics of the novel H1N1 virus. While seasonal influenza is spread by large respiratory droplets, a concern at the onset of any potential influenza pandemic is whether the pathogen will have different transmission dynamics or methods of spread (e.g. via airborne spread such as tuberculosis). Evidence for airborne transmission of seasonal influenza is lacking outside of laboratory-based experiments involving artificial aerosolization of influenza virus and rare events in closed environments with minimal air circulation and opportunities for indirect contact (e.g., airplanes). Based upon the available evidence regarding seasonal influenza transmission, the CDC Healthcare Infection Control Practices Advisory Committee (HICPAC) has recommended the use of droplet precautions when caring for patients with either suspected or confirmed seasonal influenza. HICPAC does not recommend the use of particulate respirators or negative pressure rooms for seasonal influenza, rather these measures are recommended for pathogens which are transmitted predominantly via airborne spread by small particles that remain infective over time and may be dispersed over long distances. Such ‘airborne’ spread is not clearly documented for influenza. At the onset of the 2009 novel H1N1 outbreak, the CDC recommended that healthcare workers wear a fit-tested disposable N95 respirator, disposable non-sterile gloves, gowns, and eye protection (e.g., goggles) while providing direct patient care to or collecting clinical specimens from patients with suspected or confirmed novel H1N1. Placing patients in a negative pressure room was suggested for all patient care activities if such rooms were available and was only required for performance of aerosol-generating procedures (e.g. airway suctioning, bronchoscopy, or intubation). SHEA endorsed the initial approach taken by the CDC and other organizations to recommend enhanced precautions, as the exact transmission mode of the novel H1N1 virus was not known at the outbreak’s onset. As the outbreak has evolved, additional knowledge and experience regarding the transmission dynamics and severity of novel H1N1 has become available. Consistent with current scientific knowledge concerning the dynamics of transmission of seasonal influenza, available data and clinical experiences suggest that novel H1N1 transmission also occurs, like seasonal influenza, via droplet spread.”
The SHEA statement continues, “Just as other recommendations have been revised to reflect the increased understanding of the current wave of the novel H1N1 influenza outbreak, SHEA strongly supports and encourages updating the CDC guidance on recommended infection prevention and control practices in healthcare settings for the current wave of the novel H1N1 outbreak. Based on available data and the evolution of the H1N1 outbreak, SHEA endorses implementing the same practices recommended to prevent the transmission of seasonal influenza for the novel H1N1 virus at this time. Specifically, we recommend the use of standard and droplet precautions for suspected or confirmed cases of novel H1N1 influenza; placing surgical masks on patients with suspected or confirmed novel H1N1 infection at the point of contact with the healthcare facility; placing such patients in a single room, if available, or cohorting them with other infected patients; strict adherence to hand hygiene, respiratory hygiene and cough etiquette; early recognition and identification of suspected novel H1N1-infected patients upon presentation to a healthcare facility; and restriction of visitors and healthcare workers with febrile respiratory illnesses. Negative pressure rooms are not needed for the routine care of such patients. In recent weeks, similar guidance has been recommended and implemented by an increasing number of organizations, including healthcare facilities and public health departments.”
The bottom line, according to SHEA, is that the current strain of novel H1N1 has the same transmission dynamics as seasonal influenza and should be managed accordingly based on the currently available scientific evidence. In early November, the Association for Professionals in Infection Control and Epidemiology (APIC), along with SHEA, issued a letter to President Barack Obama expressing concern over the current federal guidance surrounding the use of personal protective equipment (PPE) by healthcare workers in treating suspected or confirmed cases of 2009 H1N1 influenza. APIC reports that in its letter, it urged the Obama administration to modify the guidance to reflect the position best supported by the available science, which is first-line use of surgical masks for routine H1N1 patient care. The letter also requests an immediate moratorium on OSHA’s requirement for healthcare facilities related to the use of N95 respirators in relation to H1N1 influenza. It was pointed out that permitting OSHA to continue to enforce a policy not grounded in science will force healthcare facilities to waste time and resources while working to comply with this requirement, rather than to enact measures that will significantly benefit patient care and healthcare worker safety during this national emergency.
The letter reads in part, “... continued research concerning the route of transmission and best means of prevention is essential as the pandemic advances so that we may respond effectively should our understanding of the acquisition pathways change. But, until and unless such evidence exists, the current federal PPE guidance and OSHA requirements remain deeply flawed with considerable consequences. Due to their disconnect with scientific evidence, these documents have engendered significant confusion among healthcare professionals and facilities’ administrators; the misallocation of scarce resources to the detriment of both patient and healthcare worker protection; and the creation of skepticism toward federal public and occupational health decision-making. During this national emergency, it is imperative that federal policy applied to healthcare facilities reflect logistical and practical concerns. In addition to providing appropriate protection for all routine patient encounters, surgical masks have the great advantage of being far more readily available, more practical to implement, more likely to be worn, and less costly than N95 respirators. Indeed, requiring the use of fit-tested respirators for routine evaluation and care of all suspect cases of H1N1 influenza could lead to unintended adverse consequences for patients and healthcare workers. Examples of possible untoward effects include the unnecessary referral of patients to already overloaded emergency rooms and the exacerbation of the existing shortage of respirators thus potentially precluding their use in situations where they are needed. In addition, because the respirators are cumbersome and make it more difficult to breathe and talk, healthcare workers may avoid their use or limit the time they spend with influenza patients.”
The APIC/SHEA letter made two recommendations:
1. Modify the federal PPE guidance to reflect the position best supported by the available science—first-line use of surgical masks for routine H1N1 patient care.
2. Institute an immediate moratorium on the enforcement of OSHA’s requirement for healthcare facilities related to the use of N95 respirators in relation to H1N1 influenza. Permitting OSHA to continue to enforce a policy that is not grounded in science will force healthcare facilities to waste time and resources working to comply with a flawed requirement when they instead should be working to enact measures that will have a beneficial impact on patient care and worker safety during this national emergency.
Some members of the infection prevention community are concerned that MacIntyre’s research may have unduly influenced members of an Institute of Medicine (IOM) committee tasked with deciding whether or not healthcare workers should don N95 respirators when caring for patients with H1N1 influenza. MacIntyre was a member of the committee that wrote the IOM’s report and recommendations, released in September. The MacIntyre and Loeb studies were among the body of research considered by the committee.
In early September, the IOM committee announced that healthcare workers who interact with patients suspected or confirmed to be infected with H1N1 influenza A should wear fit-tested N95 respirators to help guard against respiratory infection by the virus. In its report, the IOM committee endorsed the current CDC guidelines for respiratory protection against the novel flu virus; however, it did state that wearing N95 respirators should be only one element of workers’ and healthcare organizations’ infection control strategies. The CDC’s guidance documents can be accessed at: http://www.cdc.gov/h1n1flu/guidance/control_measures_qa.htm
The committee acknowledged that while the CDC guidelines and the report’s recommendations are based on the best available information and evidence, scientists do not know to what extent flu viruses spread through the air or whether infection requires physical contact with contaminated fluids or surfaces. The report called for a boost in research to answer these questions and to design and develop better protective equipment that would enhance workers’ comfort, safety and ability to do their jobs.
“Based on what we currently know about influenza, well-fitted N95 respirators offer healthcare workers the best protection against inhalation of viral particles,” said committee chair Kenneth Shine, executive vice chancellor for health affairs for the University of Texas System in Austin, and former president of the Institute of Medicine. “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.”
The IOM committee’s recommendations were:
1: Use fit-tested N95 respirators: Healthcare workers (including those in non-hospital settings) who are in close contact with individuals with nH1N1 influenza or influenza-like illnesses should use fit-tested N95 respirators or respirators that are demonstrably more effective as one measure in the continuum of safety and infection control efforts to reduce the risk of infection. The committee endorses the current CDC guidelines and recommends that these guidelines should be continued until or unless further evidence can be provided to the effect 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 be conducted in accordance with OSHA regulations, and healthcare workers should use the equipment as required by regulations and employer policies.
2. Increase research on influenza transmission and personal respiratory protection: CDC centers (e.g., National Institute for Occupational Safety and Health; National Center for Immunization and Respiratory Diseases; National Center for Preparedness, Detection, and Control of Infectious Diseases), the National Institutes of Health, and other relevant federal agencies and private institutions should fund and undertake additional research to resolve the unanswered questions regarding the relative contribution of various routes of influenza transmission; fully explore the effectiveness of personal respiratory protection technologies in a variety of clinical settings through randomized clinical trials; and design and develop the next generation of personal respiratory protection technologies for healthcare workers to enhance safety, comfort, and ability to perform work-related tasks.
“I was very impressed by the work of the IOM committee tasked with addressing healthcare provider protection against 2009-H1N1 influenza virus,” says Wava Truscott, PhD, MBA, director of scientific affairs and clinical education in the Medical Sciences Department of Kimberly-Clark Health Care. “The amount of data reviewed, breadth of relevant subjects addressed, attention to detail and the time taken to understand arguments was evidence of the seriousness with which they took their responsibility to provide CDC with recommendations. The committee analyzed published studies and government data regarding influenza dispersion profiles and the capability of medical masks and respirators to provide protection. Given the infectious dose of influenza is between 10 and a few hundred viruses, and that we inhale approximately 3,000 gallons of air per day, respiratory protection is a very serious topic.”
Truscott continues, “It was quite obvious that medical masks (surgical, isolation, procedure, dental) are not appropriate for providing protection from small (<5micron) infectious droplets carried on the inhaled air currents from the gaps around masks. Another very important point emphasized is that there are huge differences in the microbial filtration effectiveness of masks. When contaminated air is pulled through the filter material (no 'gap' consideration), the penetration of aerosol particles ranged between 4 percent and 90 percent, further highlighting the statement by the IOM that, ‘the use of many of these masks is unlikely to be effective to protect against airborne protection.’ Test methods used for FDA submissions need to be more restricted to allow direct, transparent comparisons. Respirators not only fit better, but are tightly controlled for filtration capability of the material as well. Unless, that is, there are staples in the filtration body of the respirator—then all protective predictions are off as the stress of the elastic bands pulls the staples, expanding the four to eight holes created over time in use. The 2009-H1N1 virus is now in the second pandemic wave for the northern hemisphere. It has been more contagious than predicted, but less virulent than feared. We do not know if a third or fourth wave will bring a more virulent mutation of the virus. The IOM Committee had to consider this possibility when making their recommendations along with the 2009-H1N1 report to the president that stated, ‘Of all H1 subtype hemagglutinins... the 2009-H1N1 appears to be genetically most similar to those of the 1918-19 H1N1 pandemic virus,’ which had a mild first wave but vicious subsequent waves.”
Although SHEA, APIC and IDSA are pushing for revisions to the guidelines, a number of federal agencies are calling for compliance with the more stringent respiratory protection measures.
In early November, the Occupational Safety and Health Administration (OSHA) issued a compliance directive to ensure uniform procedures when conducting inspections to identify and minimize or eliminate high to very high risk occupational exposures to the H1N1 influenza virus. The directive closely follows the CDC’s guidance, and it calls for inspectors to ensure that healthcare employers implement a hierarchy of controls to reduce the risk of transmission as well as encourage vaccination and other work practices recommended by the CDC. Where respirators are required to be used, the OSHA Respiratory Protection standard must be followed, including worker training and fit-testing. Inspectors will also be looking at healthcare institutions’ ability to document healthcare workers’ exposures and medical follow-up, as well as evidence of healthcare worker training about reducing occupational risk and exposure and wearing appropriate personal protective apparel and equipment.
The CDC recommends the use of respiratory protection that is at least as protective as a fit-tested disposable N95 respirator for health care personnel who are in close contact (within 6 feet) with patients who have suspected or confirmed 2009 H1N1 influenza. Where respirators are not commercially available, an employer will be considered to be in compliance if the employer can show a good faith effort has been made to acquire respirators. Where OSHA inspectors determine that a facility has not violated any OSHA requirements but that additional measures could enhance the protection of employees, OSHA may provide the employer with a hazard alert letter outlining suggested measures to further protect workers.
“The recently announced OSHA enforcement procedures for occupational exposure to 2009 H1N1 influenza were expected,” Rupp says. “The document notes that employers are required to provide fit-tested N95 respirators for healthcare workers engaged in the routine care of patients with known or suspected H1N1 influenza. OSHA does acknowledge procedures that can be taken in the event of a respirator shortage including extended use or repeated use of respirators.”
Rupp went on to say, “SHEA maintains that the routine use of N95 respirators for the care of patients with known or suspected H1N1 influenza is neither necessary nor practical. The OSHA enforcement procedures places a burden on hospitals, EDs, clinics, and doctor’s offices that will not make healthcare workers safer but will make their jobs more difficult and will result in considerable expense to the healthcare system. In the coming weeks, as we get into the traditional cold and flu season, compliance with this regulation will become even more convoluted and difficult. As additional clinical information regarding the transmission of influenza and the role of masks versus respirators becomes available we urge the administration — including DHHS, OSHA, and the CDC — to re-evaluates their guidance. SHEA continues to urge healthcare workers to take the most important step they can to protect themselves and their family and to get vaccinated against both H1N1 and seasonal influenza as soon as vaccine is available to them.”
Loeb M et al. Surgical mask vs. N95 respirator for preventing influenza among healthcare workers: A randomized trial. JAMA. 302(17):1865-1871. Nov. 4, 2009.
Srinivasan A and Perl TM. Respiratory protection against influenza. JAMA. 2009;302(17):1903-1904. Nov. 4, 2009.