Groups at Higher Risk for Severe Illness from Novel Influenza A (H1N1) Infection

Groups of people at higher risk for severe illness from novel influenza A (H1N1) infection are thought to be the same as those people at higher risk for severe illness from seasonal influenza. These groups include:

• Children younger than 5 years old
• Persons aged 65 years or older
• Children and adolescents (younger than 18 years) who are receiving long-term aspirin therapy and who might be at risk for experiencing Reye syndrome after influenza virus infection
• Pregnant women
• Adults and children who have asthma, chronic pulmonary, cardiovascular, hepatic, hematological, neurologic, neuromuscular, or metabolic disorders such as diabetes;
• Adults and children who have immunosuppression (including immunosuppression caused by medications or by HIV)
• Residents of nursing homes and other chronic-care facilities.

1 The effectiveness of respirators and facemasks in preventing transmission of novel H1N1 (or seasonal influenza) in various settings is not known. Use of a facemask or respirator is likely to be of most benefit if used correctly and consistently when exposed to an ill person.  (Ref. a) MacIntyre CR, et al.  EID 2009;15:233-41. b) Cowling BJ, et al. Non-pharmaceutical interventions to prevent household transmission of influenza. The 8th Asia Pacific Congress of Medical Virology, Hong Kong, 26-28 February 2009.)

2 For the purpose of this document, respirator refers to N95 or any other NIOSH-certified filtering face piece respirator.

3 Persons at increased risk of severe illness from influenza (i.e. high-risk persons) include those groups at higher risk for severe illness from seasonal influenza, including:  children younger than 5 years old;  persons aged 65 years or older;  children and adolescents (younger than 18 years) who are receiving long-term aspirin therapy and who might be at risk for experiencing Reye syndrome after influenza virus infection;  pregnant women;  adults and children who have pulmonary, including asthma, cardiovascular, hepatic, hematological, neurologic, neuromuscular, or metabolic disorders, such as diabetes; adults and children who have immunosuppression (including immunosuppression caused by medications or by HIV); and, residents of nursing homes and other chronic-care facilities.

4 The optimal use of respirators requires fit testing, training and medical clearance. Proper use is recommended to maximize effectiveness. The use of facemasks may be considered as an alternative to respirators, although they are not as effective as respirators in preventing inhalation of small particles, which is one potential route of influenza transmission.  There is limited evidence available to suggest that use of a respirator without fit-testing may still provide better protection than a facemask against inhalation of small particles. Respirators are not recommended for children or persons who have facial hair (see FDA website).

5 Use of N95 respirators or facemasks generally is not recommended for workers in non-healthcare occupational settings for general work activities.  For specific work activities that involve contact with people who have influenza-like illness (ILI) (fever plus at least either cough or sore throat and possibly other symptoms like runny nose, body aches, headaches, chills, fatigue, vomiting and diarrhea), such as escorting a person with ILI, interviewing a person with ILI, providing assistance to an individual with ILI, the following are recommended: a) workers should try to maintain a distance of 6 feet or more from the person with ILI; b) workers should keep their interactions with the ill person as brief as possible; c) the ill person should be asked to follow good cough etiquette and hand hygiene and to wear a facemask, if able, and one is available; d) workers at increased risk of severe illness from influenza infection (see footnote 3) should avoid people with ILI (possibly by temporary reassignment); and, e) where workers cannot avoid close contact with persons with ILI, some workers may choose to wear a facemask or N95 respirator on a voluntary basis  (See footnote 1). When respirators are used on a voluntary basis in an occupational work setting, requirements for voluntary use of respirators in work sites can be found on the OSHA website.

6 See case definitions of confirmed, probable, and suspected novel influenza A (H1N1). Also see infection control in the health care setting. When respiratory protection is required in an occupational setting, respirators must be used in the context of a comprehensive respiratory protection program as required under OSHA’s Respiratory Protection standard (29 CFR 1910.134). This includes fit testing, medical evaluation and training of the worker.

7 “Caring” includes all activities that bring a worker into proximity to a patient with known, probable, or suspected novel H1N1 or ILI, including both providing direct medical care and support activities like delivering a meal tray or cleaning a patient’s room.

1 See definitions for confirmed, probable, and suspect novel influenza A (H1N1) infection. Also see information on infection control in health care settings.

2 Ill persons should be placed in well ventilated areas when possible and placed in areas where at least 6 feet distance can be maintained between the ill person and other well and ill persons.  Selected references:  a) Blumenfeld HL, et al.  J Clin Invest 1959;38:199-212.  b) Bridges CB, et al.  Clin Infect Dis 2003;37:1094-1101. c) Foster MG and Cookson AH.  Lancet 1918 (Nov. 2): 588-90. d) Gregg MB.  Ann NY Acad Sci 1980;353:45-53. e) WHO.  Infection prevention and control of epidemic- and pandemic-prone acute respiratory diseases in health care.  June 2007.  f) Fabian P, et al.  Plos One 2008;3:e2691.