“Employers in healthcare settings are required to provide readily available PPE to healthcare personnel (HCP), ideally at or near likely points of use,” the CDC stated. “Sizing and models should be chosen to accommodate the needs of the local workforce. Single-use PPE is not intended to be reused. Reusable items are reprocessed between uses according to manufacturer’s instructions for use.”1
Although it was not framed as such in open comments, the CDC action can be seen as the direct result of the widespread shortages and reuse of PPE when the pandemic hit the United States in 2020. The Strategic National Stockpile fell far short, supply chains broke down, and there were accusations of price gouging and hoarding locked-down stores of supplies. The situation was predictable, given similar demand surges at the onset of HIV in the 1980s and the outbreak of Ebola in 2014. As the authors of one study concluded, “The 2020 shortage of PPE was an eventuality that nonetheless came as a surprise.”2
Setting a Standard of Care
Although CDC recommendations are not regulations, they do set a standard of care. In approving the draft, the CDC’s Healthcare Infection Control Practices Advisory Committee (HICPAC) put the onus on healthcare employers to ensure healthcare workers are not left vulnerable and exposed to the next novel pathogen.
“Train and have HCP demonstrate competency in the selecting, putting on, using, removing, and disposing of PPE in a manner to prevent exposures and self-contamination,” noted the draft guidelines approved by HICPAC in November 2023.
The draft guidelines are now under CDC for review. If approved, they will be published in the Federal Register for a two-month comment period.
Trying to resolve a confusing situation, HICPAC called for getting rid of obsolete standards and embracing new thought processes on disease transmission, focusing on precautions via air and touch.
“The draft 2024 guideline updates the conceptual framework, including the recognition of a continuum of pathogen transmission by air rather than an outdated dichotomy of droplet vs. airborne transmission,” said Michael Lin, MD, MPH, co-chair of the HICPAC isolation workgroup.
When the full document is completed — HICPAC approved one major section — it will replace the 2007 CDC isolation precautions.3 HICPAC voted to approve a draft of the new guidelines, which outline the general principles and recommendations to prevent transmission but do not list measures for individual pathogens. That is a work in progress, and that section will eventually be incorporated into the guidelines.
When the COVID-19 pandemic began in 2020, the conventional wisdom was that most respiratory infections were spread primarily by larger droplets at short range, approximately three to six feet. However, it became increasingly clear in outbreak investigations that SARS-CoV-2 was spreading beyond that range, and poor ventilation was a major contributing factor.4-6 In 2021, the CDC reported that emerging science showed transmission of SARS-CoV-2 airborne viral particles can occur beyond six feet, particularly in enclosed, poorly ventilated spaces.7
Moreover, the CDC held a “listening session” with experts a few weeks before the November 2023 meeting. At the listening session, Donald Milton, MD, DrPH, professor of environmental health at the University of Maryland, said, “[It is] now widely recognized that the traditional notion that proximity equals transmission via sprays of ballistic drops called ‘droplet transmission’ was wrong. Poor ventilation compounds the problem and extends it over larger distances.”8
Wide Variations
Accordingly, the HICPAC draft guidelines reflect a new appreciation of the wide variation in particle sizes and airborne transmission over distances. In addition to calling for selective use of airborne infection isolation rooms (AIIRs) — which have negative air pressure relative to the outside hall and a higher rate of air exchanges — the HICPAC draft guidelines noted, “[We] recognize the importance of interventions such as general ventilation with sufficient delivery rates of clean air to dilute pathogens in air, local exhaust ventilation to capture pathogens at their source, and removal of infective pathogens from air such as by filtration through portable HEPA [high-efficiency particulate air] filters or by inactivation via ultraviolet germicidal irradiation. An advantage of these interventions is that they do not require individual compliance to be effective.”
Three Tiers of Air Precautions
The draft guidelines include three tiers of air transmission precautions, two of which call for the use of N95 respirators. “There is a new category for transmission through the air called Special Air Precautions, which is expected to increase the use of NIOSH [National Institute for Occupational Safety and Health]-approved, fit-tested N95 or higher-level respirators during responses to pandemic or emerging respiratory [pathogens],” Lin said.
The approved draft air precautions are outlined as follows:
• Routine Air Precautions. “[These] are focused on reducing transmission of common, often endemic, respiratory pathogens that spread predominantly over short distances based on observed patterns of transmission, and for which individuals and their communities are likely to have some degree of immunity,” the draft guidelines stated.
- HCP should use a mask at room entry and use eye protection based on standard precautions.
- Place the patient in a private room; if unavailable, then cohort.
- Rooms should be appropriately ventilated, but an AIIR is not routinely needed.
- Source control masking should be used by the patient when they leave their room (e.g., for transport to a procedure).
• Special Air Precautions. “[These] are applied to patients with a respiratory pathogen, typically new or emerging, that is not observed or anticipated to spread efficiently over long distances (such as through ventilation systems), for which infection generally leads to more than mild illness, and where immunity (or vaccine) and effective treatment are not available,” the guidelines noted.
- HCP should use a NIOSH-approved fit-tested N95 (or higher-level) respirator and eye protection on room entry.
- Place the patient in a private room. If unavailable, then cohort.
- Rooms should be appropriately ventilated, but an AIIR is not routinely needed.
- Source control masking is indicated for the patient when they leave their room (e.g., for transport to a procedure).
• Extended Air Precautions. “[These] are used when providing care to patients with pathogens that are observed to spread efficiently across long distances and over extended times, such that room air needs to be contained (e.g., prevented from moving into the hallway where individuals are not appropriately protected),” the draft guidelines stated.
- A NIOSH-approved fit-tested N95 or higher-level respirator is worn by HCP on room entry. Eye protection is used based on Standard Precautions.
- A private room is indicated.
- An AIIR is required.
- Source control masking is indicated for the patient when they leave their room.
- Travel outside the room should be limited (e.g., for necessary procedures and treatments).
Masks and Respirators
Standard surgical masks are indicated for HCP when a procedure is anticipated to create splashes or sprays to the face, as source control, and as indicated by transmission-based precautions. A fluid-resistant mask should be used in situations when splashes and sprays are anticipated. Patients with respiratory infections should wear masks for source control when leaving their rooms.
“A seal check should be performed each time an HCP puts on a fit-tested respirator to ensure that the respirator is properly seated on the face,” the guidelines stated.
In an explanatory text, HICPAC clarified that HCP may go beyond the recommendations and wear an N95 respirator for routine air isolation.
“While not required for Routine Air Precautions, HCP may choose voluntarily to wear a NIOSH-approved N95 (or higher-level) respirator, per existing federal regulations,” HICPAC noted.
This is following Occupational Safety and Health Administration (OSHA) requirements for a respiratory protection program, but several HICPAC members said it was confusing to include it in a CDC guideline.
“I think when people are using N95s in a voluntary way when only isolation masks are recommended, it’s not for source control as much as for their own protection,” said Erica Shenoy, MD, PhD, medical director of infection control at Mass General Brigham. “They’re feeling that an isolation mask is not perhaps sufficient for their protection.”
OSHA requirements or not, allowing PPE beyond the recommended level of protection could be problematic for a CDC guideline, sending a mixed message about what level is safe, Shenoy added.
In any case, many hospitals are unlikely to allow a healthcare worker to voluntarily wear an N95 respirator if a surgical mask is indicated by the CDC, said Megan Hayden, RN, MS, CNS, CIC, CPH, an ex-officio member of HICPAC representing the Centers for Medicare & Medicaid Services.
However, the statement allowing a voluntary upgrade per OSHA regs remained in the approved draft guidelines. Similarly, although an AIIR is not recommended for Special Air Precautions, healthcare facilities may consider using such rooms for pathogens with uncertain transmission characteristics. Aerosol-generating procedures and possible transmission remain a gray area.
“There is neither expert consensus, nor sufficient supporting data, to create a definitive and comprehensive list of these procedures,” the HICPAC draft stated. “Certain procedures that involve manipulation of the patient’s airway and close proximity between the patient and the HCP may increase [the] risk of pathogen transmission by air. Facilities may perform an infection control risk assessment to implement Special Air or Extended Air precautions for patients with certain target pathogens, or for all patients regardless of symptoms or confirmed infection, during certain higher-risk procedures.”
The draft guidelines noted that a risk assessment is “central” to the adoption of standard precautions. “Performing a risk assessment can be challenging, and HCP might not anticipate all potential opportunities for exposure,” the draft guidelines stated. “To reduce this risk, facilities might choose to systematically apply elements of Standard Precautions to situations recognized as likely to present a risk of pathogen transmission. For example, because it can be difficult to anticipate if a patient with a respiratory infection will cough or sneeze during an encounter, facilities may choose to implement universal use of eye protection by HCP (in addition to the already indicated mask or respirator) for the care of patients with respiratory virus infections.”
The basic components of Standard Precautions are familiar, with the following tenets outlined by the committee:
- Hand hygiene;
- Environmental cleaning and disinfection;
- Injection and medication safety;
- Risk assessment with the use of appropriate PPE (e.g., gloves, gowns, masks) based on activities performed;
- Minimizing potential exposures (e.g., having patients and visitors wear a mask when respiratory symptoms are present);
- Reprocessing of reusable medical equipment between each patient or when soiled.
REFERENCES
- Centers for Disease Control and Prevention. 2024 Guideline to Prevent Transmission of Pathogens in Healthcare Settings.
- Cohen J, van der Meulen Rodgers Y. Contributing factors to personal protective equipment shortages during the COVID-19 pandemic. Prev Med 2020;141:106263.
- Siegel JD, Rhinehart E, Jackson M, et al. 2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings.
- Groves LM, Usagawa L, Elm J, et al. Community transmission of SARS-CoV-2 at three fitness facilities — Hawaii, June-July 2020. MMWR Morb Mortal Wkly Rep 2021;70:316-320.
- Hamner L, Dubbel P, Capron I, et al. High SARS-CoV-2 attack rate following exposure at a choir practice — Skagit County, Washington, March 2020. MMWR Morb Mortal Wkly Rep 2020;69:606-610.
- Li Y, Qian H, Hang J, et al. Probable airborne transmission of SARS-CoV-2 in a poorly ventilated restaurant. Build Environ 2021;196:107788.
- Centers for Disease Control and Prevention. Scientific brief: SARS-CoV-2 transmission. Updated May 7, 2021.
- Centers for Disease Control and Prevention. 2007 Isolation Guideline Update Listening Session. Oct. 10, 2023.
New draft patient isolation guidelines recently approved by advisors to the Centers for Disease Control and Prevention emphasized that healthcare workers have N95 respirators, masks, eye protection, and other personal protective equipment readily available.
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