When to use and what type of mask, new interim guidelines from PandemicFlu.gov

Interim Guidance on Planning for the Use of Surgical Masks and Respirators in Health Care Settings during an Influenza Pandemic

October 2006

Complete information available at PandemicFlu.gov




Since the publication of the HHS Pandemic Influenza Plan (www.hhs.gov/pandemicflu/plan/) in November 2005, the U.S. Department of Health and Human Services (HHS) has received numerous comments and inquiries regarding infection control recommendations that relate to surgical mask and respirator use (e.g., N-95 respirator[a]) during an influenza pandemic. Development of authoritative responses is hampered by the lack of definitive data about the relative contributions and importance of short-range inhalational exposure, large droplet mucosal exposure, and direct inoculation via hands or inanimate objects contaminated with virus (i.e., fomites) on influenza transmission There is only limited information on optimal interventions to prevent influenza transmission and the effectiveness of interventions on an individual basis. The lack of scientific consensus has led to conflicting recommendations by public health partners. Moreover, a large amount of incorrect, incomplete, and confusing information about surgical mask and respirator use has been disseminated on the Internet and by other popular media.

The Centers for Disease Control and Prevention (CDC) is aware of no new scientific information related to the transmission of influenza viruses since the drafting of the HHS Pandemic Influenza Plan (www.hhs.gov/pandemicflu/plan/). 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. Nevertheless, in view of the practical need for clarification, CDC has re-reviewed the existing data, as described below, and has prepared interim recommendations on surgical mask and respirator use. The purpose of this document is to provide a science-based framework to facilitate planning for surgical mask and respirator use in health care settings during an influenza pandemic.

This document synthesizes traditional infection control and industrial hygiene approaches to enhancing protection of health care personnel during an influenza pandemic. It emphasizes that surgical mask and respirator use are components of a system of infection control practices to prevent the spread of infection between infected and non-infected persons. It also reflects concerns that additional precautions are advisable during a pandemic—beyond what is typically recommended during a seasonal influenza outbreak—in view of the lack of pre-existing immunity to a pandemic influenza strain, and the potential for the occurrence of severe disease and a high case-fatality rate. Extra precautions might be especially prudent during the initial stages of a pandemic, when viral transmission and virulence characteristics are uncertain, and medical countermeasures, such as vaccine and antivirals, may not be available.

The prioritization of respirator use during a pandemic remains unchanged: N-95 (or higher) respirators should be worn during medical activities that have a high likelihood of generating infectious respiratory aerosols, for which respirators (not surgical masks) offer the most appropriate protection for health care personnel. Use of N-95 respirators is also prudent for health care personnel during other direct patient care activities (e.g., examination, bathing, feeding) and for support staff who may have direct contact with pandemic influenza patients. If N-95 or other types of respirators are not available, surgical masks provide benefit against large-droplet exposure and should be worn for all health care activities involving patients with confirmed or suspected pandemic influenza. Measures should be employed to minimize the number of personnel required to come in contact with suspected or confirmed pandemic influenza patients.

This document, Interim Guidance on Planning for the Use of Surgical Masks and Respirators in Health Care Settings during an Influenza Pandemic, augments and supersedes recommendations provided in Part 2 of the HHS Pandemic Influenza Plan (www.hhs.gov/pandemicflu/plan/#part2). This interim guidance document will be updated and amended as new information about the epidemiologic characteristics of the pandemic influenza virus becomes available.

Guidance documents on planning for surgical mask and respirator use in non-health care occupations and for the general community setting during an influenza pandemic are in preparation. Infection control recommendations related to seasonal influenza (www.cdc.gov/flu/professionals/infectioncontrol/) and avian influenza A (H5N1) (www.cdc.gov/flu/avian/professional/infect-control.htm) remain unchanged. The use of surgical masks by hospitalized patients and other symptomatic persons ("source control") is covered in the CDC’s Interim Guidance for the Use of Masks to Control Influenza Transmission (www.cdc.gov/flu/professionals/infectioncontrol/maskguidance.htm).