Influenza: Nothing to Sneeze At
Seasonal flu kills 12,000 to 52,000 victims per year in the United States, and ~650,000 worldwide. Bird flu is a variant of influenza that presents a small but potentially devastating level of threat. Understanding flu and effective prevention against it are key to reducing risk. EMS can play an important role in prevention by making vaccinations accessible, by modeling good health behavior, and by educating the public.
Historical Perspective
Flu is a group of viruses that have caused large-scale outbreaks of illness for at least 2,000 years.1-3 The Spanish flu pandemic of 1918, which is widely believed to have originated in Europe or China,4-6 sickened and killed millions of people around the world and overwhelmed health systems.7 Organizations such as the Red Cross staffed ambulances and makeshift hospitals to care for victims. The Spanish flu may have played a role in the widespread occurrence of encephalitis lethargica (a rare neurological disorder) that was seen near the end of, and shortly after, the pandemic; however, more recent analyses dispute that association.8
Modern Flu Outbreaks
It’s difficult to count the exact number of deaths caused by flu each year because infection can cause death by exacerbating pre-existing conditions such as heart disease and kidney failure. However, it’s estimated that there are as many as 12,000 to 52,000 flu-related deaths annually in the U.S., and as many as > 500,000 worldwide.9-11
Spread and Presentation
Flu is spread by respiratory droplets and may be viable for hours to days, depending upon surface and air conditions.12 Signs and symptoms of flu include fever, chills, cough, sore throat, body aches, gastrointestinal distress, and fatigue.13 Mild to moderate illness can often be treated with rest, hydration, and oral medications (i.e., oral oseltamivir, inhaled zanamivir, intravenous peramivir, or oral baloxavir).14 Severe illness (i.e., fever higher than 104° F) may require hospitalization and can be fatal.
Types of Flu
Flu viruses can be grouped into four types (i.e., A, B, C, and D).15,16 Types A and B are the most likely to cause illness in humans and are the sources of seasonal outbreaks. Type C typically only causes mild illness in humans. Type D is primarily found in cattle.
Avian (Bird) Flu
Evidence suggests that bird flu has been around since at least the late 1800s.17 Originally known as fowl plague, it was later renamed avian influenza. It’s a Type A flu with several subtypes (e.g., [A]HN51). Human infections are rare, and person-to-person transmission is highly unlikely. As of 2025, a few dozen poultry flocks and dairy herds were infected with bird flu in the United States. There have been ~70 human cases in the U.S. and over 1,500 worldwide.18,19
To date, humans have not developed widespread effective immunity to avian flu. Therefore, if bird flu ever does become easily transmissible from birds to people, and worse, if it were to be easily spread from person to person, it could be the source of a devastating global pandemic. Public health agencies are constantly monitoring cases and risks associated with bird flu.
Vaccines
Edward Jenner created the first vaccine as a protection against smallpox, in 1798 (a process originally called “variolation”).20,21 The first effective flu vaccine was developed in the 1940s by Jonas Salk to address outbreaks of flu among military personnel serving in World War II.22,23 Modern flu vaccines are typically created using chickens’ eggs as the growth medium.24,25 Vaccines against seasonal flu are generally either trivalent (protective against three strains) or quadrivalent (protective against four strains). A quadrivalent vaccine will include protection against two Type A flu strains and two Type B strains of flu.
Vaccine Hesitancy
Vaccines save lives and they lessen significant sequelae. For them to be truly useful, vaccines must be received by enough people in a community to cause herd immunity.26 This is the point at which a virus has too few opportunities to infect victims for it to become a widespread concern.
Early examinations of vaccination rates among EMS personnel indicated low flu vaccine use.27,28 King et al. found 38% of healthcare workers were vaccinated against flu in 2004. Rueckman, Shah and Humiston found that only 21% were vaccinated against seasonal flu in 2009. However, Hubble, Renkiewicz, Hunter, & Kearns found that 67% of EMS workers were vaccinated against flu during the 2020-21 season.29 The CDC found 59% of people considered to be essential workers planned to be (or were) vaccinated.30 The most likely reasons for not planning on being vaccinated was simply not wanting to do so (21%) and not feeling the need for a flu vaccination (16%). Among healthcare personnel, 81% received (or planned to receive) a flu vaccination.31 Working for an employer that required vaccination appears to have made a difference. When vaccination was required, 94% of workers were vaccinated versus 70% when it was not required. Healthcare workers who were vaccinated in the previous year were more likely to be vaccinated in 2020.10
EMS Role
The "Three Cs" model of vaccine hesitancy espouses that hesitancy is a function of confidence in the vaccine (and the system that provides it), complacency toward personal health, and the level of convenience in getting the vaccine.32 People are more likely to become vaccinated if they are encouraged to do so by their healthcare provider. They are less likely to do so if they are exposed to misinformation about vaccines.
EMS has frequent contact with vulnerable populations, such as the elderly, unhoused persons, and those experiencing long-term convalescence. This presents unique opportunities for providers to play a vital role in reducing flu-related morbidity and mortality by providing access to vaccinations, educating the public about the risks of influenza, and modeling best practices.
Some states permit paramedics to administer flu vaccines.33 This means EMS can staff vaccination centers and, because they are usually in vehicles, they can take vaccines to patients who lack transportation or who live in sparsely populated areas. Vaccinations do not require a two-person crew so a single paramedic could travel in a smaller vehicle to reduce cost.
Community engagement can help identify locations for vaccination sites such as houses of worship, community centers, and private residences. Collaboration could deepen the connection between an EMS agency and the people they serve. Reaching out to community experts will help agencies navigate potential cultural and language issues (such as vaccine hesitancy rooted in cultural beliefs and language barriers that make it difficult to understand vaccine information).
Education campaigns should focus on offering easy-to-understand short presentations in multiple formats. Colorful posters, engaging radio messages and videos should be created and disseminated. Content should be created using well-respected objective sources.
EMS personnel should promote vaccine acceptance by publicly acknowledging that they themselves are vaccinated. Serving as role models can help to increase the public’s confidence in vaccinations. Agency personnel should be well versed in vaccination science to be able to respond to misinformation or hesitancy.
Summary
Flu kills tens of thousands of people in the U. S. every year, and hundreds of thousands around the world. Emergency personnel are potentially exposed to pathogens every time they work. If exposed, these workers can be a vector for spreading flu from one patient to another, to a colleague, or to a loved one. Best practices in reducing the risks of flu include frequent handwashing, self-quarantining or isolation, and vaccination.
EMS must be involved in public education about flu and in the overall strategy to provide preventive services. As a highly educated and mobile health service, EMS can help reduce the spread of flu and to lessen the impacts of infection in their community.
References
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2. Who and When to Vaccinate Against Influenza. Buchy, P., & Badur, S. International Journal of Infectious Diseases, Vol. 93, pp. 375–387.
3. Lindsay, S and & Yin, J. Anti-Viral Assays for Diagnosis and Drug Development. Bio Tech International. April - May 2009, Vol. 21, 2, pp. 11-14.
4. Breitnauer, J. The Spanish Flu Epidemic and Its Influence on History. South Yorkshire : Pen & Sword History, 2019. p. 4.
5. U.S. Centers for Disease Control and Prevention. History of 1918 Flu Pandemic. [Online] March 21, 2018. [Cited: June 21, 2021.] https://www.cdc.gov/flu/pandemic-resources/1918-commemoration/1918-pandemic-history.htm.
6. Paths of Infection: The First World War and the Origins of the 1918 Influenza Pandemic. Humphries, M. 1, War in History , Vol. 21, pp. 55-81.
7. U.S. Centers for Disease Control and Prevention. 1918 Pandemic Influenza Historic Timeline. [Online] March 20, 2018. [Cited: June 29, 2021.] https://www.cdc.gov/flu/pandemic-resources/1918-commemoration/pandemic-timeline-1918.htm.
8. The Relationship Between Encephalitis Lethargica and Influenza: A Critical Analysis. McCall, S., Vilensky, J.A., Gilman, S., & Taubenberger, J.K. 3, May 17, 2009, Journal of Neurovirology, Vol. 14, pp. 177-185.
9. Marcia, A., McElhaney, J., Chaves, S., Nealon, J, Nunes, M., Samson, S., Seet, B., Weinke, T. & Yu, H. The Disease Burden of Influenza Beyond Respiratory Illness. Vaccine. June 11, 2021, Vol. 39, 1, pp. A6 - A14.
10. Utilizing the Theory of Planned Behavior to determine the intentions to receive the influenza vaccine during COVID-19: A cross-sectional survey of US adults. Chu, A., Gupta, V., & Unni, E. J. 2021, Preventive Medicine Reports, Vol. 23, p. 101417.
11. World Health Organization. Influenza (Seasonal). World Health Organization. [Online] 2025. [Cited: April 14, 2025.] https://www.who.int/westernpacific/health-topics/influenza-seasonal#tab=tab_1.
12. Mayo Clinic. Cold and flu viruses: How long can they live outside the body? [Online] February 2, 2024. [Cited: March 24, 2026.] https://www.mayoclinic.org/diseases-conditions/flu/expert-answers/infectious-disease/faq-20057907.
13. U.S. Centers for Disease Control and Prevention. Flu Symptoms & Complications. [Online] August 26, 2024. [Cited: March 10, 2026.] https://www.cdc.gov/flu/signs-symptoms/?CDC_AAref_Val=https://www.cdc.gov/flu/symptoms/symptoms.htm.
14. U.S. Centers for Disease Control and Prevention. Influenza Antiviral Medications: Summary for Clinicians. [Online] March 10, 2026. [Cited: March 10, 2026.] https://www.cdc.gov/flu/hcp/antivirals/summary-clinicians.html.
15. World Health Organization. Influenza (Avian and other zoonotic). [Online] 2021. https://www.who.int/news-room/fact-sheets/detail/influenza-(avian-and-other-zoonotic).
16. U. S. Centers for Disease Control and Prevention. Types of Influenza Viruses. Infuenza (Flu). [Online] September 26, 2025. [Cited: March 11, 2026.] https://www.cdc.gov/flu/about/viruses-types.html?CDC_AAref_Val=https://www.cdc.gov/flu/about/viruses/types.htm.
17. Highlights in the History of Avian Influenza (Bird Flu). CDC.gov. [Online] June 1, 2024. [Cited: March 10, 2025.] https://www.cdc.gov/bird-flu/avian-timeline/index.html.
18. H5 Bird Flu: Current Situation. Avian Influenza (Bird Flu). [Online] April 4, 2025. [Cited: April 7, 2025.] https://www.cdc.gov/bird-flu/situation-summary/index.html.
19. Fisher, J. Bird flu: Where we are now and what to know about prevention. Harvard Health Publishing: Harvard Medical School. [Online] February 25, 2025. [Cited: March 10, 2025.] https://www.health.harvard.edu/diseases-and-conditions/bird-flu-where-we-are-now-and-what-to-know-about-prevention.
20. Equination (inoculation of horsepox): An early alternative to vaccination (inoculation of cowpox) and the potential role of horsepox virus in the origin of the smallpox vaccine. Esparza, J., Schrick, L., Damaso, C. R., & Nitsche, A. 52, December 17, 2017, Vaccine, Vol. 35, pp. 7222–7230.
21. Beyond the Myths: Novel Findings for Old Paradigms in the History of the Smallpox Vaccine. Esparza, J., Nitsche, A and & Damaso, A. 7, July 26, 2018, PLoS Pathogens , Vol. 14, pp. 1-6.
22. Vaccines today, vaccines tomorrow: a perspective. Loucq, C. 1, 2013, Clinical & Experimental Vaccine Research, Vol. 2, pp. 4-7.
23. Experience with Vaccination Against Influenza in the Spring of 1947: A Preliminary Report. Thomas, F., Salk, J., & Quilligan, J.J. 37, August 1947, Proceedings of the National Academy of Sciences, Vol. 111, pp. 12283-12287. 1013-1016.
24. U. S. Centers for Disease Control and Prevention. Flu Vaccine and People with Egg Allergies. [Online] September 17, 2024. [Cited: March 11, 2026.] https://www.cdc.gov/flu/prevent/egg-allergies.htm.
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26. Understanding vaccine hesitancy: the evidence. While, A. 6, June 2021, British Journal of Community Nursing, Vol. 26, pp. 278-282.
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28. Brief report: Influenza vaccination and health care workers in the United States. King, W. D., Woolhandler, S. J., Brown, A. F., Jiang, L., Kevorkian, K., Himmelstein, D. U., & Bor, D. H. 1, 2006, Journal of General Internal Medicine, Vol. 22, pp. 181-184.
29. Predictors of COVID-19 Vaccination Among EMS Personnel. Hubble, M., Renkiewicz, G. K., Hunter, S., & Kearns, R. D. 4, July 2022, Western Journal of Emergency Medicine, Vol. 23, pp. 570-577.
30. U.S. Centers for Disease Control and Prevention. Early-Season Influenza Vaccination Uptake and Intent Among Adults – United States, September 2020. [Online] August 28, 2024. [Cited: March 11, 2026.] https://www.cdc.gov/fluvaxview/coverage-by-season/early-season-uptake-sept-2020.html?CDC_AAref_Val=https://www.cdc.gov/flu/fluvaxview/nifs-estimates-sept2020.htm.
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32. Influenza Vaccination Hesitancy in Large Urban Centers in South America. Qualitative Analysis of Confidence, Complacency and Convenience across Risk Groups. González-Block, M.A., Pelcastre-Villafuerte, B. E., Knauth, D.R., Fachel-Leal, K. A., Comes, Y., Crocco, P., Noboa, L., Rodriguez Zea, B. Ruoti, M., Diaz Portillo, & S. P., Sarti, E. 8, August 2021, PLoS ONE, Vol. 16, pp. 1-23.
33. Massachusetts Department of Public Health Office of Emergency Medical Services. Special Protocol. Special Protocol Influenza Vaccine. [Online] [Cited: July 15, 2024.] https://www.mass.gov/doc/special-protocol-for-ems-personnel-flu-vaccination-under-commissioners-order-december-18-2020/download.
