Oct 18, 2006 (CIDRAP News) – The US Department of Health and Human Services (HHS) has issued new guidance calling for stronger respiratory protection for healthcare workers in the event of an influenza pandemic.
A new interim guidance document says the use of N-95 respirators—designed to stop 95% of small airborne particles—is "prudent" for medical workers providing any direct care for patients ill with confirmed or suspected pandemic flu and is recommended in caring for those with pneumonia. It also says respirator use is prudent for support workers in direct contact with patients.
In contrast, HHS's pandemic influenza plan issued last November recommends that healthcare workers wear simple surgical masks, designed to block large respiratory droplets, for routine care of pandemic flu patients. Both the pandemic plan and the new guidance recommend using an N-95 respirator or similar protection during procedures likely to generate airborne infectious particles, such as endotracheal intubation.
The new document also advises healthcare facilities to expect and plan for shortages of N-95 respirators and similar protective equipment in the event of a pandemic.
The new recommendation reflects increased concern about the possibility of airborne transmission of flu viruses, though the document says the Centers for Disease Control and Prevention (CDC) has found no new scientific evidence on the question. HHS says the new guidance "augments and supersedes" the advice in the pandemic flu plan.
HHS has received many questions and comments about mask and respirator use since it issued its pandemic plan, the document says. Scientific debate on the issue has led to conflicting recommendations by public health agencies, while wrong, incomplete, and confusing information has flourished online and in the news media, the agency says.
The new advice comes less than a month after a Canadian expert asserted in a CDC journal that the US, Canadian, and British plans for pandemic flu didn't give strong enough advice on respiratory protection for healthcare workers.
The CDC "is aware of no new scientific information related to the transmission of influenza viruses since the drafting of the HHS Pandemic Influenza Plan," the new guidance states. "As stated in the plan, the proportional contribution and clinical importance of the possible modes of transmission of influenza (i.e., droplet, airborne, and contact) remains unclear and may depend on the strain of virus ultimately responsible for a pandemic."
But because of the need for "practical clarification," the CDC decided to review the evidence again and issue recommendations "to provide a science-based framework to facilitate planning for surgical mask and respirator use" during a pandemic.
The new document is titled "Interim Guidance on Planning for the Use of Surgical Masks and Respirators in Health Care Settings during an Influenza Pandemic." It says that "convincing evidence of airborne transmission of influenza viruses from person to person over long distances (e.g., through air-handling systems, or beyond a single room) has not been demonstrated."
But it adds, "Although data are limited, the possibility remains that short-range aerosol transmission is a route of influenza transmission in humans and requires further study."
The report recommends that healthcare workers caring for pandemic flu patients use respirators rated at N-95 or higher during activities likely to generate infectious aerosols, such as intubation, nebulizer treatment, bronchoscopy, and resuscitation. In addition, a respirator should be used when providing any kind of direct care for a confirmed or suspected pandemic flu patient who has pneumonia, because such patients may produce unusual amounts of infectious particles when they cough.
Further, the guidance says, "Use of N-95 respirators for other direct care activities involving patients with confirmed or suspected pandemic influenza is also prudent. Hospital planners should take this into consideration during planning and preparation in their facilities when ordering supplies."
By comparison, the 2005 HHS pandemic plan advises medical workers, "Wear a [surgical] mask when entering a patient's room." Aerosol-generating procedures are the only activities in which N-95 respiratory protection is clearly recommended, according to the HHS plan. However, it says the precaution "may be considered" when dealing with highly transmissible flu strains, during the early stages of an outbreak of a new strain, and in other special circumstances.
The new guidance also warns hospital officials to anticipate shortages of respirators. Because such shortages are likely in a sustained pandemic, planners should take care to save enough respirators for use during high-risk procedures, without depriving workers who need them for other activities, it says. It also says managers should take steps to minimize the number of personnel exposed to pandemic flu patients, such as establishing specific wards for such patients.
"If supplies of N-95 (or higher) respirators are not available, surgical masks can provide benefits against large droplet exposure, and should be worn for all health care activities for patients with confirmed or suspected pandemic influenza," the guidance states.
The new recommendations represent "an important step forward," according to infectious disease expert Michael T. Osterholm, PhD, MPH, director of the University of Minnesota Center for Infectious Disease Research and Policy, which publishes the CIDRAP Web site. "The CDC is acknowledging that we have a lot of questions that aren't answered and that aerosol transmission may play a role" in the spread of flu.
"This is another example of where the dogma that has existed for years about transmission is being challenged," he added.
Osterholm said the new advice implies that respiratory protection may be important for more than just healthcare workers. "If it is prudent for healthcare workers to be wearing N-95s, then you have to also consider that [step] as the baseline for protection for anyone who might come into contact with influenza," he said.
"But having said that, we all know that there'll be an inadequate number of respirators for use even by healthcare workers," he said. Still, the prospect of shortages shouldn't be a reason for avoiding frank discussion of the evidence about how flu viruses spread, he added.
See also:
HHS's "Interim Guidance on Planning for the Use of Surgical Masks and Respirators in Health Care Settings during an Influenza Pandemic"
Sep 29 CIDRAP News article "Airborne flu viruses threaten health workers, expert says"
