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Interim Guidance on Environmental Management of Pandemic Influenza Virus
Influenza A and B viruses can persist on both nonporous and porous environmental surfaces for hours to days depending on a variety of human and environmental factors. The secondary spread of infectious virus from environmental reservoirs to susceptible persons is accomplished primarily via hand transfer (i.e., hand contact with contaminated surfaces and then touching mucous membranes of the eyes, nose, and mouth). Proper handwashing or hand hygiene, coupled with respiratory hygiene and cough etiquette is the principal means of interrupting this transfer. Routine cleaning and disinfection strategies used during influenza seasons could be applied to the environmental management of pandemic influenza, if such an event were to occur. Laundry and solid waste management could be performed as usual.
While some assumptions can be made about the behavior of a pandemic virus, the exact characteristics of the virus cannot be known in advance. Influenza viruses are genetically variable, and transmissibility is difficult to predict. As a result, this guidance is subject to change as the unique epidemiologic characteristics of a pandemic influenza virus become known during the course of the pandemic period. Although seasonal influenza A and B viruses are not thought to spread predominantly via airborne routes of transmission, it is possible that a pandemic influenza virus may exhibit properties that would facilitate airborne transmission. Should this occur, environmental management strategies may be revised to incorporate measures to prevent exposure to infectious aerosols.
Influenza viruses are transmitted person to person predominantly via mucous membrane exposure to infectious respiratory secretions discharged initially as large droplets (a form of direct contact). These droplets can transmit influenza virus to susceptible persons present in the occupied space within 6 feet from the source patient. Large droplets, however, tend to settle out of the air in a relatively short period and eventually come to rest on a variety of environmental surfaces. Environmental surfaces in homes, healthcare facilities, schools, and other places of business include, but are not limited to, large housekeeping surfaces (e.g., floors, walls, windows, tables and countertops), equipment and appliances, and surfaces frequently touched by hand (e.g., door handles, light switches, bathroom and kitchen surfaces, phones, computers). Aerosolization of virus (i.e., production of tiny particles) from respiratory secretions can occur, but exposure to these particles is not considered to be a primary means of spread.
Influenza A and B viruses can persist on dry environmental surfaces, both porous and nonporous. Laboratory studies conducted to evaluate this persistence document survival periods that vary widely in length, depending on environmental factors. Low relative humidity levels (e.g., < 50%) and cool, ambient temperatures are associated with longer periods of activity. Influenza A virus can survive on hard, nonporous surfaces (e.g., stainless steel, hard plastic) for 24 – 48 hours and on porous materials (e.g., cloth, paper) for < 8 – 12 hours in ambient temperatures (1). Virus persistence on surfaces increases up to 72 hours when those surfaces are moist or wet (2). Early laboratory studies with the PR-8 strain of influenza virus recovered infectious virus from cotton fabric after several weeks (3). However, the extent to which these surfaces and materials contributed to actual spread of infection was not determined. Influenza virus persistence on hands also varied widely. One early study demonstrated that dried influenza virus can persist on hands for at least 3 hours (4), whereas more recent studies have shown that virus can remain stable on the hands for < 5 minutes (1). Infectious virus can be transferred to hands from nonporous surfaces for at least 2 – 8 hours during periods of heavy viral shedding in respiratory secretions (1). Virus transfer from porous materials to the hands is much less efficient, being severely affected by rapid drying. In this instance, infectious virus was transferred at detectable levels to the hands for only 15 minutes (1).
A recent study has demonstrated the potential for widespread dispersion of influenza viruses to a variety of frequently touched surfaces in homes and child care centers (5). This study used reverse transcriptase polymerase chain reaction (RT-PCR) to detect influenza virus A RNA on surfaces. While this study did not evaluate the viability of influenza virus, it did demonstrate the extent to which virus can contaminate the environment, especially when infected persons are present and actively shedding virus in respiratory secretions. Influenza viral RNA was detected frequently on surfaces such as refrigerator handles, phone receivers, TV remotes, and other surfaces in kitchens (e.g., microwave ovens). Viral RNA was found less frequently on toys in day care centers, and this may be due to day care center policies addressing the routine cleaning of toys (5).
Environmental surfaces can serve as reservoirs of infectious virus, although there is no evidence that influenza virus infection can be transmitted directly from environmental surfaces. While there is little or no evidence to support the potential for significant resuspension of influenza viruses into the air from objects and surfaces, hand transfer of virus from surfaces to mucous membranes is estimated to be an important factor in the transmission of influenza virus infection among groups of people (e.g., coworkers, family members). Transfer of non-influenza respiratory viruses from objects and environmental surfaces to hands has been demonstrated in several laboratory studies (6 – 8). Another study using bacteriophage ΦX174 showed how virus can be spread in a simulated household setting via the hands of volunteer participants (9).
Cleaning and disinfection can reduce the numbers of viruses present on environmental surfaces, which can help to minimize hand transfer of virus (10). Influenza viruses are enveloped, lipid-containing viruses, and as such are readily sensitive to a wide variety of chemical disinfectants (Figure 1) (11). While historically there has been a clear distinction between pandemic strains of influenza viruses and seasonal influenza viruses based on antigenic specificity, there is no new evidence to suggest that pandemic influenza viruses are biophysically or biochemically different than seasonal influenza virus. Although pandemic influenza viruses may cause severe disease, influenza viruses are among the least resistant microorganisms to chemical disinfection. Therefore, routine cleaning and disinfection strategies used during influenza seasons could be applied for the environmental management of pandemic influenza.
Figure 1. Relative Resistance Levels of Microorganisms to Chemical Disinfection (High to Low Levels in Descending Order)
Non-lipid or small viruses
Lipid or medium-sized viruses
Cleaning with soap or detergent in water is the first step in surface treatment. Cleaning will remove soil and organic matter that would otherwise reduce the effectiveness of the disinfection step that follows. There is no indication for cleaning procedures that differ from what is done routinely. Any commercially available soap or detergent can be used. Water can be cold or warm, or as recommended on the label of the cleaning product used (if a specific temperature is listed).
Influenza viruses can be inactivated by many low- or intermediate level disinfectants containing any of the following ingredients (12):
- chlorine or hypochlorite
- quaternary ammonium compounds [quats]
- peroxygen compounds
Use of disinfectants registered by the U.S. Environmental Protection Agency (EPA) is recommended whenever these are available. Lists of all registered disinfectants can be found at http://www.epa.gov/oppad001/chemregindex.htm. Many, if not all, of these products indicate potency for several target pathogens on the label. There are approximately 400 registered disinfectants with human influenza A and/or B listed on the product label, and all will inactivate influenza viruses when used according to manufacturer instructions.
The basic strategies for management of environmental surfaces in healthcare facilities are discussed in the CDC/HICPAC “Guidelines for Environmental Infection Control in Health-Care Facilities,” published in 2003 (13). Additional guidance is available from the World Health Organization (14). The guidance that follows is drawn from these resources.
- Environmental Services staff should use appropriate personal protective equipment (PPE) (i.e., household gloves) as needed when preparing disinfectant and cleaning solutions and when applying these solutions by hand to wipes and/or surfaces.
- Clean and disinfect surfaces that are touched routinely by hand (e.g., doorknobs, bed rails, bedside- and over-bed tables, bathroom surfaces, safety/pull-up bars, television controls, call buttons) on a more frequent schedule than that used for large housekeeping surfaces.
- Follow manufacturer instructions for proper use of disinfectants, especially with regards to the proper concentration of product and the time the product should be in contact with the surface being disinfected.
- Consult medical equipment instructions for appropriate methods of cleaning and disinfection for these items, and consider using barrier coverings for equipment that may be hard to clean or has accessible electronic components.
- Clean large housekeeping surfaces (e.g., floors) in patient-care areas with detergent/disinfectants in accordance with manufacturer instructions on a regular basis as per facility policy (i.e., at least daily and terminally cleaned at patient discharge).
- Avoid large-surface cleaning methods that produce mists or aerosols or disperse dust in patient-care areas (e.g., use wet dusting techniques, wipe application of cleaning and/or disinfectant solutions).
- Detergent and water are adequate for cleaning surfaces in nonpatient-care areas (e.g., administrative offices).
- Follow facility procedures to ensure the cleanliness of cleaning and/or disinfectant solutions, rinse water, mop heads, and cloths (e.g., separate buckets for solutions and rinse water, frequent exchanges of solutions, replacing soiled mops heads and cloths with clean items, using microfiber mopping methods).
- Avoid placing influenza patients in rooms with carpeting if possible; use vacuums equipped with HEPA filtration when vacuuming carpets in patient-care areas.
- Educate patients, staff, and visitors about the importance of handwashing and hand hygiene, emphasizing “hand awareness” (i.e., touching nose, mouth, or eyes after touching a potentially contaminated surface or object) (15, 16).
The adherence to good personal hygiene, proper hand hygiene, respiratory hygiene, and cough etiquette is especially important for preventing the spread of influenza in non-healthcare settings in the community (16). Schools may dismiss classes, and businesses may consider implementing social distancing as an influenza control strategy early on during a moderate or severe influenza pandemic (17, 18). While school remains in session and when businesses reduce onsite staffing, environmental infection control for non-healthcare settings focuses on regular cleaning for most surfaces and targeted use of disinfection for surfaces touched frequently by hand:
- Keep housekeeping surfaces and countertops clean of visible soil by cleaning with detergents and water or proprietary cleaners, followed by rinsing with water. Repeated application of disinfectants to table and desktop surfaces is unnecessary. Frequent use of room air deodorizers to disinfect the air is not recommended.
- Follow label instructions carefully when using disinfectants and cleaners, noting any hazard advisories and indications for using personal protective items (such as household gloves). Do not mix disinfectants and cleaners unless the labels indicate it is safe to do so. Combining certain products (such as chlorine bleach and ammonia cleaners) can be harmful, resulting in serious injury or death.
- Clean and disinfect bathroom surfaces on a regular basis using EPA-registered detergent/disinfectants. Alternatively, clean surfaces first with detergent and water and then disinfect with an EPA-registered disinfectant in accordance with manufacturer instructions. (Note: Disinfectant products available in grocery stores or hardware stores are all EPA-registered.)
- If EPA-registered disinfectants are not available, use a dilute solution (1:100 volume/volume, approximately 600 parts per million [ppm]) of household chlorine bleach (sodium hypochlorite) to disinfect bathroom surfaces. To prepare this solution, add ¼ cup of bleach to a gallon of clean water, or 1 tablespoon of bleach to a quart of clean water. Apply to a cleaned surface, preferably with a cloth moistened with the bleach solution, and allow the surface to remain wet for minimally 3 – 5 minutes (13).
- Clean and disinfect commonly touched surfaces in the home with a detergent/disinfectant in accordance with label instructions (e.g., microwaves, refrigerator door handles, door handles).
- Wipe frequently touched electronic items (e.g., remote controls, hand-held gaming devices) with hand-sanitizer cloths.
- Carry hand-sanitizer cloths in cars to use on hands and surfaces in cars.
Although influenza viruses can persist on porous materials, the transfer of these viruses from sheets, bedding, and clothing is not as efficient a process as that involving non-porous surfaces (1). Therefore, management of laundry in healthcare facilities and in the home can be accomplished with existing procedures appropriate for these settings (13, 14):
- Handle soiled clothing and linens during collection with a minimum amount of agitation and fluffing;
- Healthcare workers and laundry personnel should follow established facility safety procedures (minimum recommendation is for glove use) when handling soiled linens.
- Handwashing or hand hygiene should be done in the home after sorting laundry and adding the clothing and linens to the washer.
- Use detergents, laundry additives, and appropriate water temperature as per routine laundry procedures. Follow manufacturer instructions for detergent and bleach use.
- Use a temperature setting for drying clothes and linens appropriate for the fabrics in the load. Line- or air-drying can be used to dry items when machine drying is not indicated.
- Clean your hands before removing clean laundry from the washer or dryer, especially if you have coughed or sneezed onto your hands.
There is no evidence to suggest that either pandemic influenza virus or seasonal influenza viruses can be spread via contact with either routine solid wastes or regulated medical wastes generated either in a healthcare facility or in a home, school, or business. Therefore, current waste management strategies can continue to be used while influenza viruses are in circulation (13, 14):
- Healthcare Facilities:
- Use Standard Precautions when working with solid waste that may be contaminated with influenza virus outside of patient isolation areas.
- Use PPE as is currently required by your state (e.g., gloves) when handling open waste containers.
- No changes in waste containment need be made during periods of influenza activity (e.g., single bag lining for routine clinic wastes, appropriate labeled containment for regulated medical wastes).
- Current medical waste treatment procedures can be used to treat regulated medical waste in accordance with state and federal regulations.
- Treated medical waste can be safely deposited in municipal solid waste landfills as per normal procedures.
- Homes, Schools, and Businesses:
- Disposable tissues used to contain coughs, sneezes, or nasal discharges can be tossed in waste receptacles; no special precautions are required.
- Handwashing or hand hygiene should be done after emptying these waste containers.
- Barring specific state routine solid waste or medical waste regulations to the contrary, these wastes are considered routine solid wastes in the community that can be sent to municipal solid waste landfills without treatment.
1. Bean B, Moore BM, Sterner F, Peterson LR, Gerding DN, Balfour HH Jr. Survival of influenza viruses on environmental surfaces. J Infect Dis 1982; 146: 47-51.
2. Barker J, Stevens D, Bloomfield SF. Spread and prevention of some common viral infections in community facilities and domestic homes. J Appl Microbiol 2001; 91: 7-21.
3. Edward DG. Resistance of influenza virus to drying and its demonstration on dust. Lancet 1941; 241: 664-6.
4. Parker ER, MacNeal WJ. Persistence on influenza virus on the human hand. J Lab Clin Med 1944; 29: 121-6.
5. Boone SA, Gerba CP. The occurrence of influenza A virus on household and day care center fomites. J Infect Dis 2005; 51: 103-9.
6. Hall CB, Douglas RG Jr, Geiman JM. Possible transmission by fomites of respiratory syncytial virus. J Infect Dis 1980; 141: 98-102.
7. Brady MT, Evans J, Cuartas J. Survival and disinfection of parainfluenza viruses on environmental surfaces. Am J Infect Control 1990; 18: 18-23.
8. Ansari SA, Stringthorpe VS, Sattar SA, Rivard S, Rahman M. Potential role of hands in the spread of respiratory viral infections: Studies with human parainfluenza virus 3 and rhinovirus 14. J Clin Microbiol 1991; 29: 2115-9.
9. von Rheinbaben F, Schünemann S, Groß T, Wolff MH. Transmission of viruses via contact in a household setting: Experiments using bacteriophage ΦX174 as a model virus. J Hosp Infect 2000; 46: 61-6.
10. Sattar SA, Jacobsen H, Springthorpe VS, Cusack TM, Rubino JR. Chemical disinfection to interrupt transfer of rhinovirus type 14 from environmental surfaces to hands. Appl Environ Microbiol 1993; 59: 1579-85.
11. Favero MF, Bond WW. Chemical disinfection of medical and surgical materials. In: Disinfection, Sterilization, and Preservation, 4th Edition, SS Block (ed.). Lea & Febiger; Philadelphia, PA; 1991: p. 617-41.
12. Prince HN, Prince DL. Principles of viral control and transmission. In: Disinfection, Sterilization, and Preservation, 5th Edition, SS Block (ed.). Lippincott, Williams & Wilkins; Philadelphia, PA; 2001: p. 543-71.
13. Centers for Disease Control and Prevention. Guidelines for environmental infection control in health-care facilities: Recommendations of CDC and the Healthcare Infection Control Advisory Committee (HICPAC). MMWR 2003; 52 (No. RR-10): 1-48. (See also the full text version of this guideline at http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5210a1.htm).
14. World Health Organization. Infection prevention and control in health care for confirmed or suspected cases of pandemic (H1N1) 2009 and influenza-like illnesses: interim guidance 25 June 2009. Accessed 2 March 2012 at: http://www.who.int/csr/resources/publications/SwineInfluenza_infectioncontrol.pdf
15. Centers for Disease Control and Prevention. Guideline for hand hygiene in health-care settings: Recommendations of the Healthcare Infection Control Practices Advisory Committee and the HICPAC/SHEA/APIC/IDSA Hand Hygiene Task Force. MMWR 2002; 51 (RR-16): 1-45.
16. Centers for Disease Control and Prevention. Stopping the spread of germs at home, work, and school. Accessed 5 October 2006 at: http://www.cdc.gov/flu/protect/stopgerms.htm
17. World Health Organization Writing Group. Nonpharmaceutical interventions for pandemic influenza national and community measures. Emerg Infect Dis 2006; 12: 88-94.
18. Centers for Disease Control and Prevention. Interim pre-pandemic planning guidance: Community strategy for pandemic influenza mitigation in the United States – Early, targeted, layered use of nonpharmaceutical interventions. Accessed 29 May 2007 at: http://www.flu.gov/professional/community/community_mitigation.pdf