Introduction

Concerns about the COVID-19 coronavirus outbreak—first detected in China, in late 2019—have prompted ECRI Institute to reissue some of its past guidance related to infectious disease outbreaks. In the current moment, we believe healthcare professionals will find it instructive to revisit issues associated with the 2003 outbreak of severe acute respiratory syndrome (SARS).
 

Background

In 2003, more than 8,000 people worldwide contracted SARS—a respiratory illness that usually begins with a fever, progresses to include other symptoms, and can lead to the development of pneumonia. During the initial outbreak, 774 deaths were attributed to the disease. In less than two months at the start of 2020, the impact of the novel coronavirus (2019-nCoV) that causes COVID-19 has far surpassed those totals. COVID-19 is spreading faster than SARS did, and has already infected tens of thousands of patients. COVID-19 appears to progress with relatively mild symptoms at first, then develops to pneumonia and potentially to acute respiratory distress syndrome (ARDS), which is hard to treat and often requires the patient to be put on a ventilator (advanced life support).

The mechanism of SARS-CoV transmission was understood to be associated with close contact with a SARS-infected person or exposure to large-droplet secretions from an infected person's cough or sneeze. As reported in The Lancet (subscription or fee required for access) in mid-February 2020, "presently COVID-19 seems to spread from person to person by the same mechanism as other common cold or influenza viruses—ie, face to face contact with a sneeze or cough, or from contact with secretions of people who are infected."

In the case of SARS, transmission of the disease was quickly controlled, and the outbreak was declared over by July 2003. Nevertheless, concern existed that SARS could in fact be a seasonal disease and that another outbreak could occur in later years. The threat of another outbreak underscored the importance of facilities having a response plan in place to safeguard the health of their communities and staff members. ECRI Institute produced a series of articles in 2003 and 2004 discussing the risks associated with SARS, reviewing recommendations from the U.S. Centers for Disease Control and Prevention (CDC), discussing the role of hospital facilities departments and clinical engineers in SARS preparations, and updating ECRI's recommendations for infection control procedures during equipment servicing.

What follows is an excerpt of that content produced during the SARS outbreak. While the information was produced with that specific instance in mind, much of the information would likewise apply to other outbreaks of infectious diseases. Note that in some places, we have updated links or references to other material that has been published since this article was issued.

Source: ECRI Institute. Protecting against SARS during equipment maintenance. Health Devices 2003 Jun;32(6):216.
 

Advice for Equipment Servicers and Other Hospital Personnel

When respiratory protection is required to prevent the spread of disease (such as SARS or tuberculosis) from infectious patients to medical personnel, the most commonly used device is an N95 respirator.[1] This is a mask that fits over the mouth and nose, typically held in place by elastic bands. The mask material is designed to allow air to pass, but to block 95% of particles 0.3 microns in diameter under specified test conditions.

The N95 respirator is relatively inexpensive and disposable. However, it has some significant disadvantages. One is the fact that protection depends on a proper fit to the wearer's face; before the first use, the mask must be fit-tested to verify that a proper seal has been obtained. Even with fit-testing, significant leakage occurs into the mask through the face-to-facepiece seal (adding a further inefficiency of 10% or more to the existing 5% inefficiency of the filter). Additional disadvantages are that the wearer must be trained in proper use and must receive medical clearance to use the mask (for example, because the mask increases breathing effort) and that the mask can be uncomfortable if worn for a considerable time.

Increased protection can be attained through the use of an N99 or N100 respirator mask. This increase is based solely on the greater efficiency of the mask's filtering material; the face-to-facepiece seal will be the same as that for an N95 mask. In fact, all tight-fitting negative-pressure air-purifying respirators, including the filtering-facepiece type (e.g., N95, N99, and N100 respirators) half-face respirators, have an inherent face-to-facepiece seal inefficiency of 10%.

If still greater protection is desired, a loose-fitting, powered air-purifying respirator (PAPR) can be used. This device consists of a Tyvek headcover/hood and faceshield that fits over the head, along with a blower unit to blow filtered room air into a mask worn by the user. Because of the positive pressure maintained in the mask, protection does not depend on maintaining a tight seal to the face. Though it costs much more than an N95 mask (a loose-fitting PAPR costs several hundred dollars; an N95 mask costs less than two dollars), advocates of the PAPR claim that costs may be comparable or even less than those of the N95, for two reasons: (1) a PAPR is reusable, and (2) since a PAPR is a loose-fitting respirator, fit-testing is not required under the U.S. Occupational Safety and Health Administration's (OSHA) respiratory protection standard 29 CFR 1910.134, saving a considerable amount of time and expense. Advocates also state that a loose-fitting PAPR is more comfortable to wear for a long time.

Hospitals will need to perform their own assessment and select the most appropriate protection, if required, based on hospital policies and individual circumstances and—in the United States—in compliance with 29 CFR 1910.132 and 134.

Additional information on respirator selection is available online from the National Institute for Occupational Safety and Health (NIOSH); see www.cdc.gov/niosh.

Update: As of February 3, 2020, CDC recommends, in the case of the COVID-19 outbreak, that staff "use respiratory protection (i.e., a respirator) that is at least as protective as a fit-tested NIOSH-certified disposable N95 filtering facepiece respirator before entry into the patient room or care area." That recommendation matches the guidance ECRI Institute initially issued (in June 2003) in the case of the 2003 SARS outbreak.

Note, however, that respiratory protection recommendations can evolve over time. For example, as new information about airborne transmission of SARS became available and as concern lessened, we updated our recommendations for that circumstance: In February 2004, we specified that it would be prudent for personnel working with the equipment to wear a surgical mask, but that there was no significant benefit to using an N95 respirator for that application, particularly in light of the considerable time and effort that respirator use entails. It is unknown at this time if similar changes will develop in the case of the COVID-19 outbreak.

________________________

[1] A surgical mask does not offer adequate respiratory protection and is not a substitute for an N95 respirator. However, a surgical mask can be used in situations where the primary concern is splash and splatter (e.g., protection against bloodborne pathogens), and in some cases surgical masks are recommended to be worn by SARS patients who can tolerate them to minimize droplet transmission into the room.