CDC draft urges universal masking of incoming patients to prevent SARS

A good rationale, but totally impractical?’

Draft guidance by public health officials preparing for a seasonal resurgence of severe acute respiratory syndrome (SARS) calls for taking the controversial step of masking all incoming patients with respiratory symptoms, Hospital Infection Control has learned.

The draft plan under consideration by the Centers for Disease Control and Prevention (CDC) underscores the need for "enhanced respiratory hygiene in the SARS era." Dormant but dreaded, SARS could make a seasonal resurgence that would be compounded by the presence of other respiratory conditions that can be spread via respiratory droplets (e.g., influenza, respiratory syncytial virus, and Mycoplasma pneumoniae).

"To help prevent transmission of respiratory infections in the health care setting, all patients presenting with respiratory symptoms should be given a surgical mask and encouraged to wear it," the CDC SARS draft plan stated.1 "These patients should also be separated, as possible, from other patients. Patients who cannot wear a surgical mask should be given tissues and instructed to cover their nose and mouth when coughing or sneezing. Patients with respiratory symptoms should then be managed under droplet precautions until it is determined that the cause of the symptoms is not an infectious agent that requires precautions."

The CDC met Sept. 12, 2003, in Atlanta with liaison representatives of numerous medical associations to solicit reaction and input on the proposed plan, Guidance for SARS Preparedness and Response in Healthcare Facilities.

"Infection control is critical," said Dan Jernigan, MD, a medical epidemiologist in the CDC division of health care quality promotion. "Universal masking and hand hygiene of respiratory patients at first encounter is important."

In most cases, it appears that contact and droplet precautions along with eye protection have been effective in preventing SARS transmission. Contact precautions emphasize hand hygiene, gloves, and gowns. Droplet precautions call for wearing a mask within three feet of the patient to prevent large particle droplet spread via coughing, sneezing, or talking. In addition, airborne transmission — though thought to be rare — may occur with SARS. Health care workers have been advised previously to wear N95 tuberculosis respirators when caring for SARS patients, particularly during aerosol-generating procedures such as intubation.

The CDC plan is expected to be finalized in the near future, but the feedback and concern evidenced at the recent meeting suggests further revisions may be in store.

The universal masking recommendation and questions about N95 respirators dominated many of the infection control conversations at the consultants’ meeting. For example, William Scheckler, MD, representing the CDC’s Healthcare Infection Control Practices Advisory Committee, expressed concern about the universal masking recommendation. "The practicality of that from the point of view of having staff to do it, isn’t clear to me," he said. "I would like to know if there are any data on influenza outbreaks or other events in adults where this has been done and proven useful. If there are no data anywhere that it is useful, particularly when you do not have a SARS outbreak or SARS cases in you community, I just wonder if this is a good idea with a good rationale but totally impractical."

The CDC guidelines also recommend that "triage and intake staff should be offered the option of wearing masks during times when respiratory infections are common and instructed to practice frequent hand hygiene. Ideally, triage staff should remain at least 3 feet away from unmasked patients with respiratory symptoms in order to decrease the risk of droplet transmission."

However, Bill Borwegen, representing the Service Employees International Union in Washington, DC, questioned why — particularly in light of documented transmission incidents to Canadian workers in Toronto — the CDC document did not place more emphasis on the use of N95 respirators to protect workers.

"If you really want to protect health care workers, you have to give them N95 respirators," he said. "I don’t know what the cost is, but we are the richest country in the world. Why is the health care sector different from any other sector of the economy? We would give workers better respiratory protection in any other sector, why not health care?"

The CDC should clarify whether supplies of N95 masks are going to be adequate and urge hospitals to begin acquiring and fit-testing them, he said.

Still, the accumulated evidence suggests the bulk of transmission is large droplet as opposed to airborne, meaning a surgical mask could actually protect the worker in a couple of key ways, said Michael Tapper, MD, representing the Society for Healthcare Epidemiology of America.

"The surgical mask probably functions to prevent the health care worker from touching his or her nose or mouth, which is probably very important for preventing transmission [of] large droplets," he said. "I would agree with you [Borwegen], where an organism is spread by airborne droplet nuclei such as tuberculosis or measles that a surgical mask is totally inadequate. For a disease that seems to be largely spread by droplet or by contact, a surgical mask — by covering the nose and the mouth and preventing the health care worker from inadvertently touching these areas, as well as blocking large droplets — offers significant protection."

The CDC officials expressed little enthusiasm for the role of diagnostic testing as an immediate clinical indicator, noting that — just as with tuberculosis — testing in areas of low SARS prevalence primarily would yield false positives. The issue has not been resolved, but the CDC is considering recommending SARS testing after 72 hours if no other diagnosis has been made. In lieu of immediate testing, epidemiological questioning is emphasized in the draft guidance.

"Clinically — just taking the clinical features — there is no way we can tell who has SARS and who doesn’t," said John Jernigan, MD, medical epidemiologist in the CDC division of health care quality promotion. "The epidemiological link is going to be the most helpful thing. Epidemiology has got to be part of the work-up for pneumonia from now on."

To do that, even if SARS is not circulating, the draft recommended that patients hospitalized for radiographically confirmed pneumonia be questioned about three situations:

  1. travel to or close contact with ill people with a history of travel to previously SARS-effected areas within 10 days of illness onset;
  2. employment as a health care worker with direct patient care responsibilities;
  3. any close contacts recently found to have evidence of pneumonia on chest X-ray without an alternative diagnosis.

The CDC estimates that the vast majority of pneumonia patients will answer no to all three questions. But if the patient answers yes to any of the questions, clinicians should contact the health department and initiate a diagnostic algorithm designed by the CDC. (See algorithm.)

Why the health care worker question? The emergence of SARS was marked so distinctly by nosocomial and occupational spread that pneumonia in health care workers may be followed in CDC surveillance systems as a sentinel event. Still, the new epidemiology emphasis will not be easy if past experience with TB is any indication, said Allison McGeer, MD, a Toronto-based epidemiologist who represented Canada at the meeting.

"SARS is like TB, only less forgiving," she said. "You have the same problems. You have to look at the clinical features and think epidemiologically, but [nothing] is absolute. If you are willing to isolate eight or 10 patients for every [TB]-infected patient [diagnosed], you do fine. But it has been very hard for us to implement, and SARS is just like that. The difficulty is not ultimately sorting out who has SARS and who doesn’t. The course of disease in general will tell you that. It is the fact that the initial assessment is going to be made by people who don’t have epi’ on the brain."

All facilities should be ready

The CDC prefers that all hospitals prepare for SARS at some basic level — even before any cases return — rather then try to have designated SARS facilities in individual communities. "SARS plans should be part of existing disaster preparedness plans," Dan Jernigan said. "Hospitals spent a lot of time and money getting ready for smallpox and bioterrorism. SARS should be incorporated."

SARS preparedness and response planning can be done by an existing hospital group or committee such as the infection control committee or a bioterrorism task force, the CDC draft stated. "Because SARS control efforts will require a coordinated response from both health care facilities and public health officials, the [hospital response] team should identify a contact in the local health department who will serve as a liaison both for SARS preparedness planning and response, should cases occur," the guidelines state. "If possible, this person should sit on the hospital planning committee."

Concerning SARS responsibilities within the hospital, James Bentley, of the American Hospital Association, urged the CDC not to assign the plan to a specific individual or group in all hospitals. "Half the hospitals in this country have [fewer than] 100 beds," he said. "We need to get this into the institutions, but it is very hard for us to say [where specifically it should be assigned as an area of responsibility.]"

Scheckler strongly disagreed, saying infection control professionals are working — at least part time — in small rural and community hospitals.

"If this, as an infectious disease, isn’t connected in an important way with the infection control team in a hospital — with the support of the administration — then you are missing the one group that knows something and could actually implement it," he said. "I think we make a mistake if we didn’t at least make the suggestion that the most logical place in most hospitals would be in infection control."

Bentley conceded that a "suggestion" would be appropriate. McGeer gave real-world weight to the ICP discussion when she underscored the mistakes made during the Toronto outbreak. "From my perspective, we paid very dearly in Toronto for having underfunded and underresourced infection control departments," she said.

The situation got so bad that Toronto hospitals were appealing to American epidemiologists and ICPs to cross the border and help them, she recalled. "What most infection control practitioners and hospital epidemiologists did during SARS was answer one long stream of questions for 23 hours a day," McGeer said. "There wasn’t enough of us to do that."

The key is having pre-existing relationships between ICPs, hospitals, and public health officials. "If those are in place ahead of time you can manage things," McGeer said "When they are not in place is when we get into trouble."

That trouble may be starting again in Singapore, where a lab worker apparently has a mild case of SARS that may have been occupationally or community acquired. If it is the latter, it raises the question of whether "there are other undetected cases out there," said Simon Mardell of the World Health Organization.

Regardless, SARS is a "headline from nature" that foreshadows the inevitable things to come, McGeer emphasized. "SARS is only the warning shot across the bow," she said. "Pandemic influenza is coming. If we fail to take advantage and learn from this, it is going to be really hard."


1. Centers for Disease Control and Prevention. Draft document. Guidance for SARS Preparedness and Response in Healthcare Facilities. Atlanta; Sept. 9, 2003.