Influenza prevention

From WikiProjectMed
Jump to navigation Jump to search


Influenza prevention involves taking steps that one can use to decrease their chances of contracting flu viruses, such as the Pandemic H1N1/09 virus, responsible for the 2009 flu pandemic.


Sneezing can transmit influenza.

People who contract influenza are most infective between the second and third days after infection, and infectivity lasts for around ten days.[1] Children are much more infectious than adults and shed virus from just before they develop symptoms until two weeks after infection.[1][2] The transmission of influenza can be modeled mathematically, which helps predict how the virus will spread in a population.[3]

Influenza can be spread in three main ways:[4][5]

  • by direct transmission (when an infected person sneezes mucus directly into the eyes, nose or mouth of another person);
  • the airborne route (when someone inhales the aerosols produced by an infected person coughing, sneezing or spitting);
  • through hand-to-eye, hand-to-nose, or hand-to-mouth transmission,[6] either from contaminated surfaces or from direct personal contact such as a hand-shake.

The relative importance of these three modes of transmission is unclear, and they may all contribute to the spread of the virus.[7][8] In the airborne route, the droplets that are small enough for people to inhale are 0.5 to 5 µm in diameter and inhaling just one droplet might be enough to cause an infection.[4] Although a single sneeze releases up to 40,000 droplets,[9] most of these droplets are quite large and will quickly settle out of the air.[4] How long influenza survives in airborne droplets seems to be influenced by the levels of humidity and UV radiation: with low humidity and a lack of sunlight in winter probably aiding its survival.[4]

As the influenza virus can persist outside of the body, it can also be transmitted by contaminated surfaces such as banknotes,[10] doorknobs, light switches and other household items.[11] The length of time the virus will persist on a surface varies, with the virus surviving for one to two days on hard, non-porous surfaces such as plastic or metal, for about fifteen minutes from dry paper tissues, and only five minutes on skin.[12] However, if the virus is present in mucus, this can protect it for longer periods.[4] Avian influenza viruses can survive indefinitely when frozen.[13] They are inactivated by heating to 56 °C (133 °F) for a minimum of 60 minutes, as well as by acids (at pH <2).[13]

Novel H1N1

According to the World Health Organization (WHO), the "main route of transmission of the pandemic influenza virus seems to be similar to seasonal influenza, via droplets that are expelled by speaking, sneezing or coughing."[14] One of WHO's recommendations is to "keep your distance from people who show symptoms of influenza-like illness, such as coughing and sneezing (trying to maintain a distance of about 1 metre if possible)."[14] Other WHO recommendations are listed below.

The American Centers for Disease Control and Prevention (CDC) agrees that the "spread of novel H1N1 virus is thought to occur in the same way that seasonal flu spreads. Flu viruses are spread mainly from person to person through coughing or sneezing by people with influenza."[6] The CDC also says that a person may become infected if he or she touches something with flu viruses on it "and then touches his or her eyes, nose, or mouth."[6]

Researchers have demonstrated anti-bodies against H1N1 variant influenza in 10 to 7 percent of workers and residents of swine farms in Jiangsu Province, China. Residents of a nearby city did not have detectable anti-bodies to H1N1 variant influenza.[15]


Reasonably effective ways to reduce the transmission of influenza include good personal health and hygiene habits such as: not touching your eyes, nose or mouth;[6] frequent hand washing (with soap and water, or with alcohol-based hand rubs);[6] covering coughs and sneezes; avoiding close contact with sick people; and staying home yourself if you are sick. Avoiding spitting is also recommended.[16]

Although face masks might help prevent transmission when caring for the sick,[17][18] there is mixed evidence on beneficial effects in the community.[16][19] Smoking raises the risk of contracting influenza, as well as producing more severe disease symptoms.[20][21][22][23][24] Thus, according to the laws of mathematical modelling of infectious diseases, smokers raise the exponential growth rates of influenza epidemics and may indirectly be responsible for a large percentage of influenza cases.[citation needed]

Since influenza spreads through both aerosols and contact with contaminated surfaces, surface sanitizing may help prevent some infections.[25] Alcohol is an effective sanitizer against influenza viruses, while quaternary ammonium compounds can be used with alcohol so that the sanitizing effect lasts for longer.[26] In hospitals, quaternary ammonium compounds and bleach are used to sanitize rooms or equipment that have been occupied by patients with influenza symptoms.[26] At home, this can be done effectively with a diluted chlorine bleach.[27]

Social distancing strategies used during past pandemics, such as closing schools, churches and theaters, slowed the spread of the virus but did not have a large effect on the overall death rate.[28][29] It is uncertain if reducing public gatherings, by for example closing schools and workplaces, will reduce transmission since people with influenza may just be moved from one area to another; such measures would also be difficult to enforce and might be unpopular.[16] When small numbers of people are infected, isolating the sick might reduce the risk of transmission.[16]

According to studies conducted in Australia and Japan, screening individuals for influenza symptoms at airports during the 2009 H1N1 outbreak was not an effective method of infection control.[30][31]


The Centers for Disease Control and Prevention (CDCP) recommends that businesses promote and administer annual flu vaccination within the workplace. Additional measures include reducing potential for exposure through increasing awareness of flu symptoms, using good cough and sneeze etiquette, staying home when ill, and frequent hand washing.[32]

The Occupational Health and Safety Administration (OSHA) recommends these controls to employers to decrease transmission of influenza in the workplace:[33]

  • Promotion, administration, and easy access to the flu vaccine
  • Encourage sick workers to stay home
  • Hand hygiene and cough etiquette
  • Use airborne infection isolation rooms, when appropriate
  • Ensure properly functioning heating, ventilation, and air conditioning (HVAC) systems
  • Limit transport of infected patients
  • Limit the number of staff who come in contact with flu patients
  • Provide personal protective equipment (PPE) such as gloves, gowns, masks, to health care staff as well as disposal facilities

Specific occupations with increased risk of influenza infection include health care, education and child care, air line industry, and agricultural workers.

Recommended behaviours

WHO recommendations

According to the WHO, you can decrease your chance of contracting the flu virus by taking the following steps:[14]

  • Get yourself (or family members age 6 months and older) vaccinated against current strains of influenza, if possible.
  • Keep your distance from people who show symptoms of influenza-like illness, such as coughing and sneezing (trying to maintain a distance of about 1 metre if possible);
  • Clean your hands thoroughly with soap and water, or cleanse them with an alcohol-based hand rub on a regular basis (especially if touching surfaces that are potentially contaminated);
  • Avoid touching your mouth, nose and eyes as much as possible;
  • Reduce the time spent in crowded settings if possible;
  • Improve airflow in your living space by opening windows;
  • Practice good health habits (including adequate sleep, eating nutritious food, and keeping physically active)
CDCP recommendations

The CDCP lists these as important ways to lower the risk of transmission:[6]

  • Cover the nose and mouth with a tissue when coughing or sneezing. Throw tissues in the trash after use;
  • Wash hands often with soap and water, especially after coughing or sneezing. Alcohol-based hand cleaners are also effective;
  • Avoid touching the eyes, nose, or mouth. Germs spread this way;
  • Try to avoid close contact with sick people;
  • Those sick with flu-like illness are recommended to stay home for at least 24 hours after their fever is gone, except to get medical care or for other necessities. (The fever should be gone without the use of a fever-reducing medicine.) The sickened are advised to keep away from others as much as possible to avoid making others sick.


Watch for emergency warning signs that need urgent medical attention. These warning signs include:[citation needed]

  • Fast breathing or trouble breathing
  • Bluish or gray skin color
  • Not drinking enough fluids
  • Not urinating or no tears when crying
  • Severe or persistent vomiting
  • Not waking up or not interacting
  • Being so irritable that the child does not want to be held
  • Pain or pressure in the chest or abdomen
  • Sudden dizziness
  • Confusion
  • Flu-like symptoms improve but then return with fever and worse cough[34]

Vaccination against H1N1

In the 2009 pandemic, the initial demand for vaccine greatly outstripped the supply.[35]

2,500 people line up in a mall in Texas City, Texas to receive the H1N1 vaccine from the Galveston County Health Department.

As the 2009 pandemic got underway, the first vaccine to become available in the United States by mid-October 2009 was about 2.2 million doses of the weakened live-virus nasal spray formulation. This form was not then recommended for some of the people who at highest risk of complications from flu, including pregnant women and people with asthma.[citation needed] The attenuated live virus was instead suggested to be used to allow some priority groups like health care workers and healthy children 2 or older, to allow them to be vaccinated immediately. Those to whom the weakened virus might pose a heightened risk were recommended to wait for the release of killed-virus vaccines, which followed weeks to months later.[citation needed]

Vaccine uptake by the public was very low in the UK, but predicted by greater belief in the vaccine's efficacy and safety and a greater perceived risk of the disease.[36]

Public opinion

A survey of Americans done in late June 2009 by the Harvard School of Public Health found that roughly 90% said they would be willing to avoid shopping malls, movie theaters, public transportation, and worship services for more than two weeks if health officials told them to. It also found that parents were worried about closures of schools or day care centers, with 43% saying they would lose pay or have money problems if they had to stay home a week or more because they were sick or had to care for someone.[37][38] In the UK, the government established a National Pandemic Flu Service with a hotline and website, enabling persons with symptoms to get advice or obtain drugs without first getting a prescription from a doctor.[39]

Increased risk of transmission for agriculture workers

Individuals with increased exposure to animals, especially birds and swine, are at increased risk of variant influenza infection. This includes agricultural workers, as well as residents of farms, individuals who keep swine and/or birds as pets, and animal exhibitors. Variant influenza viruses do not normally infect humans, but when they do cause human infection, the virus can be passed from animals to humans directly, or between humans.[40] Due to human to human transmission, family and close contacts of agricultural workers are at increased risk of influenza as well. Unfortunately, there is also decreased access to health care in agricultural communities which makes prevention and response to influenza outbreaks more difficult.[41] During the 2009 H1N1 pandemic, multiple factors were identified as increasing the vulnerability of agricultural workers and their communities. These factors included substandard housing, immigration status, scape-goating, economic barriers, communication and cultural barriers, and discrimination.[41][42] Steege et al., found that 75% of agricultural workers were uninsured, making them less likely to receive the flu vaccine and less likely to seek care when ill.[42]

Public health recommendations for agricultural communities:[42]

  • surveillance of agricultural workers
  • Inclusion of agricultural workers in prevention efforts and planning
  • Separating ICE from emergency services
  • Increased access to influenza vaccination
  • Risk reduction training (cough etiquette, etc.)
  • PPE use
  • Workplace Sanitation

Recommendations for agricultural workers and exhibitors:[43]

  • Influenza vaccination
  • Limit time swine are kept on the fairgrounds to no more than 72 hours
  • Wash hands with soap and water when leaving the barn
  • Restrict food and drink in animal area
  • Do not sleep in animal areas

Additional recommendations for visitors to agricultural exhibits:[15]

  • High Risk:
    • Defined as people younger than 5 years, older than 65 years, pregnant women, and people with chronic illnesses.
    • Avoid pigs and swine barns
  • Low Risk:
    • Don't eat, drink, or apply anything to your mouth in pig areas
    • Don't take toys, pacifiers, cups, baby bottles, strollers, or similar items into pig areas
    • Avoid close contact with pigs that look or act ill
    • Use gloves, protective clothing, masks if contact with ill pigs
    • Wash your hands often with soap and running water before and after exposure to pigs. If soap and water are not available, use an alcohol-based hand rub.
    • Watch your pig(s) for signs of illness. Call a veterinarian if you suspect illness.
    • Avoid contact with pigs if you have flu symptoms. Wait until you have been fever-free for 7 days or until you have been without fever for 24 hours without taking temperature-reducing medications; whichever is longer
    • If you become ill, contact a health care provider. Let them know you are higher risk and about any recent exposure to pigs or swine barns. The same medications that are used for seasonal flu can be used for variant virus infection.

See also


  1. 1.0 1.1 Carrat, Fabrice; Luong, Julie; Lao, Hervé; Sallé, Anne-Violaine; Lajaunie, Christian; Wackernagel, Hans (2006). "A 'small-world-like' model for comparing interventions aimed at preventing and controlling influenza pandemics". BMC Medicine. 4: 26. doi:10.1186/1741-7015-4-26. PMC 1626479. PMID 17059593.
  2. Mitamura, Keiko; Sugaya, Norio (2006). "Diagnosis and Treatment of influenza". Uirusu. 56 (1): 109–16. doi:10.2222/jsv.56.109. PMID 17038819.
  3. Grassly, Nicholas C.; Fraser, Christophe (2008). "Mathematical models of infectious disease transmission". Nature Reviews Microbiology. 6 (6): 477–87. doi:10.1038/nrmicro1845. PMC 7097581. PMID 18533288.
  4. 4.0 4.1 4.2 4.3 4.4 Weber, Thomas P.; Stilianakis, Nikolaos I. (2008). "Inactivation of influenza a viruses in the environment and modes of transmission: A critical review". Journal of Infection. 57 (5): 361–73. doi:10.1016/j.jinf.2008.08.013. PMC 7112701. PMID 18848358.
  5. Hall, C. B. (2007). "The Spread of Influenza and Other Respiratory Viruses: Complexities and Conjectures". Clinical Infectious Diseases. 45 (3): 353–9. doi:10.1086/519433. PMC 7107900. PMID 17599315.
  6. 6.0 6.1 6.2 6.3 6.4 6.5 Center for Disease Control and Prevention: "QUESTIONS & ANSWERS: Novel H1N1 Flu (Swine Flu) and You" Archived 2010-03-04 at the Wayback Machine Retrieved December 13, 2009
  7. Tellier, Raymond (2006). "Review of Aerosol Transmission of Influenza a Virus". Emerging Infectious Diseases. 12 (11): 1657–62. doi:10.3201/eid1211.060426. PMC 3372341. PMID 17283614.
  8. Brankston, Gabrielle; Gitterman, Leah; Hirji, Zahir; Lemieux, Camille; Gardam, Michael (2007). "Transmission of influenza a in human beings". The Lancet Infectious Diseases. 7 (4): 257–65. doi:10.1016/S1473-3099(07)70029-4. PMID 17376383.
  9. Cole, Eugene C.; Cook, Carl E. (1998). "Characterization of infectious aerosols in health care facilities: An aid to effective engineering controls and preventive strategies". American Journal of Infection Control. 26 (4): 453–64. doi:10.1016/S0196-6553(98)70046-X. PMC 7132666. PMID 9721404.
  10. Thomas, Y.; Vogel, G.; Wunderli, W.; Suter, P.; Witschi, M.; Koch, D.; Tapparel, C.; Kaiser, L. (2008). "Survival of Influenza Virus on Banknotes". Applied and Environmental Microbiology. 74 (10): 3002–7. Bibcode:2008ApEnM..74.3002T. doi:10.1128/AEM.00076-08. PMC 2394922. PMID 18359825.
  11. "Influenza: Viral Infections: Merck Manual Home Edition". Archived from the original on 2008-03-17. Retrieved 2008-03-15.
  12. Bean, B.; Moore, B. M.; Sterner, B.; Peterson, L. R.; Gerding, D. N.; Balfour, H. H. (1982). "Survival of Influenza Viruses on Environmental Surfaces". Journal of Infectious Diseases. 146 (1): 47–51. doi:10.1093/infdis/146.1.47. PMID 6282993.
  13. 13.0 13.1 "Influenza Factsheet" (PDF). Center for Food Security and Public Health, Iowa State University. Archived (PDF) from the original on 2009-03-23. Retrieved 2022-08-27. p. 7
  14. 14.0 14.1 14.2 World Health Organization: "What Can I Do?" Retrieved January 20, 2010
  15. 15.0 15.1 Yin, Xiuchen; Yin, Xin; Rao, Baizhong; Xie, Chunfang; Zhang, Pengchao; Qi, Xian; Wei, Ping; Liu, Huili (April 2014). "Antibodies against avian-like A (H1N1) swine influenza virus among swine farm residents in eastern China: Antibodies Against Avian Like H1N1 Swine Influenza Virus". Journal of Medical Virology. 86 (4): 592–596. doi:10.1002/jmv.23842. PMID 24497077. S2CID 20037718.
  16. 16.0 16.1 16.2 16.3 Aledort, Julia E; Lurie, Nicole; Wasserman, Jeffrey; Bozzette, Samuel A (2007). "Non-pharmaceutical public health interventions for pandemic influenza: An evaluation of the evidence base". BMC Public Health. 7: 208. doi:10.1186/1471-2458-7-208. PMC 2040158. PMID 17697389.
  17. MacIntyre, C. Raina; Cauchemez, Simon; Dwyer, Dominic E.; Seale, Holly; Cheung, Pamela; Browne, Gary; Fasher, Michael; Wood, James; Gao, Zhanhai; Booy, Robert; Ferguson, Neil (2009). "Face Mask Use and Control of Respiratory Virus Transmission in Households". Emerging Infectious Diseases. 15 (2): 233–41. doi:10.3201/eid1502.081167. PMC 2662657. PMID 19193267.
  18. Weinstein, R. A.; Bridges, C. B.; Kuehnert, M. J.; Hall, C. B. (2003). "Transmission of Influenza: Implications for Control in Health Care Settings". Clinical Infectious Diseases. 37 (8): 1094–101. doi:10.1086/378292. PMID 14523774.
  19. "Interim Guidance for the Use of Masks to Control Influenza Transmission". CDC. August 1, 2009. Archived from the original on December 2, 2019. Retrieved August 27, 2022.
  20. Murin, S.; Bilello, K. S. (2005). "Respiratory tract infections: Another reason not to smoke". Cleveland Clinic Journal of Medicine. 72 (10): 916–20. doi:10.3949/ccjm.72.10.916. PMID 16231688.
  21. Kark, Jeremy D.; Lebiush, Moshe; Rannon, Lotte (1982). "Cigarette Smoking as a Risk Factor for Epidemic A(H1N1) Influenza in Young Men". New England Journal of Medicine. 307 (17): 1042–6. doi:10.1056/NEJM198210213071702. PMID 7121513.
  22. Finklea, J. F.; Sandifer, S. H.; Smith, D. D. (1969). "Cigarette smoking and epidemic influenza". American Journal of Epidemiology. 90 (5): 390–9. doi:10.1093/oxfordjournals.aje.a121084. PMID 5356947.
  23. Kark, J. D.; Lebiush, M (1981). "Smoking and epidemic influenza-like illness in female military recruits: A brief survey". American Journal of Public Health. 71 (5): 530–2. doi:10.2105/ajph.71.5.530. PMC 1619723. PMID 7212144.
  24. Nicholson, K. G.; Kent, J; Hammersley, V (1999). "Influenza a among community-dwelling elderly persons in Leicestershire during winter 1993-4; cigarette smoking as a risk factor and the efficacy of influenza vaccination". Epidemiology and Infection. 123 (1): 103–8. doi:10.1017/s095026889900271x. JSTOR 4617449. PMC 2810733. PMID 10487646.
  25. Weinstein, R. A.; Hota, B. (2004). "Contamination, Disinfection, and Cross-Colonization: Are Hospital Surfaces Reservoirs for Nosocomial Infection?". Clinical Infectious Diseases. 39 (8): 1182–9. doi:10.1086/424667. PMC 7107941. PMID 15486843.
  26. 26.0 26.1 McDonnell, G; Russell, A. D. (1999). "Antiseptics and disinfectants: Activity, action, and resistance". Clinical Microbiology Reviews. 12 (1): 147–79. doi:10.1128/CMR.12.1.147. PMC 88911. PMID 9880479.
  27. "Chlorine Bleach: Helping to Manage the Flu Risk". Water Quality & Health Council. April 2009. Archived from the original on 2009-06-07. Retrieved 2009-05-12.
  28. Hatchett, R. J.; Mecher, C. E.; Lipsitch, M. (2007). "Public health interventions and epidemic intensity during the 1918 influenza pandemic". Proceedings of the National Academy of Sciences. 104 (18): 7582–7. Bibcode:2007PNAS..104.7582H. doi:10.1073/pnas.0610941104. PMC 1849867. PMID 17416679.
  29. Bootsma, M. C. J.; Ferguson, N. M. (2007). "The effect of public health measures on the 1918 influenza pandemic in U.S. Cities". Proceedings of the National Academy of Sciences. 104 (18): 7588–93. Bibcode:2007PNAS..104.7588B. doi:10.1073/pnas.0611071104. PMC 1849868. PMID 17416677.
  30. Gunaratnam, Praveena J; Tobin, Sean; Seale, Holly; Marich, Andrew; McAnulty, Jeremy (2014). "Airport arrivals screening during pandemic (H1N1) 2009 influenza in New South Wales, Australia". The Medical Journal of Australia. 200 (5): 290–2. doi:10.5694/mja13.10832. PMID 24641156.
  31. Nishiura, Hiroshi; Kamiya, Kazuko (2011). "Fever screening during the influenza (H1N1-2009) pandemic at Narita International Airport, Japan". BMC Infectious Diseases. 11: 111. doi:10.1186/1471-2334-11-111. PMC 3096599. PMID 21539735.
  32. "Prevention Strategies for Seasonal Influenza in Healthcare Settings". CDC. October 5, 2016. Archived from the original on August 29, 2022. Retrieved August 27, 2022.
  33. "Safety and Health Topics | Seasonal Flu – Employer Guidance – Reducing Healthcare Workers' Exposures to Seasonal Flu Virus | Occupational Safety and Health Administration". Archived from the original on 2019-10-24. Retrieved 2019-10-24.
  34. "CDC H1N1 Flu | Action Steps for Parents of Children at High Risk for Flu Complications". Archived from the original on 2017-05-10. Retrieved 2022-08-27.
  35. "Vaccination Against H1N1 to Become Universal". 2009-10-06. Archived from the original on 2011-06-06. Retrieved 2009-10-06.
  36. Weston, Dale; Blackburn, Ruth; Potts, Henry W.W.; Hayward, Andrew C. (2017). "Predictors of self and parental vaccination decisions in England during the 2009 H1N1 pandemic: Analysis of the Flu Watch pandemic cohort data". Vaccine. 35 (31): 3875–3882. doi:10.1016/j.vaccine.2017.05.061. PMC 5593150. PMID 28606815.
  37. "Survey Finds Just 40% of Adults "Absolutely Certain" They Will Get H1N1 Vaccine". October 2, 2009. Archived from the original on October 25, 2009. Retrieved October 23, 2009.
  38. "Survey: Americans expect widespread swine flu ahead". USA Today. Atlanta, Georgia, USA. AP. 2009-07-16. Archived from the original on 2009-08-26. Retrieved 2009-09-27.
  39. "Adverts promote swine flu service". BBC. 2009-07-24. Archived from the original on 2009-08-07. Retrieved 2009-09-17.
  40. "Variant Influenza Viruses: Background and CDC Risk Assessment and Reporting | CDC". 2018-10-09. Archived from the original on 2019-10-24. Retrieved 2019-10-24.
  41. 41.0 41.1 Schoch-Spana, Monica; Bouri, Nidhi; Rambhia, Kunal J.; Norwood, Ann (September 2010). "Stigma, Health Disparities, and the 2009 H1N1 Influenza Pandemic: How to Protect Latino Farmworkers in Future Health Emergencies". Biosecurity and Bioterrorism: Biodefense Strategy, Practice, and Science. 8 (3): 243–254. doi:10.1089/bsp.2010.0021. ISSN 1538-7135. PMID 20825335.
  42. 42.0 42.1 42.2 Steege, Andrea L.; Baron, Sherry; Davis, Shelley; Torres-Kilgore, Judith; Sweeney, Marie Haring (October 2009). "Pandemic Influenza and Farmworkers: The Effects of Employment, Social, and Economic Factors". American Journal of Public Health. 99 (S2): S308–S315. doi:10.2105/ajph.2009.161091. ISSN 0090-0036. PMC 4504372. PMID 19797742.
  43. Stewart, R. J.; Rossow, J.; Conover, J. T.; Lobelo, E. E.; Eckel, S.; Signs, K.; Stobierski, M. G.; Trock, S. C.; Fry, A. M.; Olsen, S. J.; Biggerstaff, M. (2017-11-16). "Do animal exhibitors support and follow recommendations to prevent transmission of variant influenza at agricultural fairs? A survey of animal exhibitor households after a variant influenza virus outbreak in Michigan". Zoonoses and Public Health. 65 (1): 195–201. doi:10.1111/zph.12425. ISSN 1863-1959. PMC 6631301. PMID 29143461.

External links