Influenza

Influenza, commonly known as the flu, is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and lungs and can cause mild to severe illness. Serious outcomes of flu infections can result in hospitalization or death.¹ The best way to prevent the flu is by getting vaccinated every year.

Most often present in the fall and winter, the flu can reach epidemic proportions in many geographic areas and communities. According to the CDC, each year, between 3,000 and 49,000 Americans die from influenza-related complications, depending on the severity and length of each flu season.²

Three types of influenza viruses infect humans: Influenza A, B, and C. Type A and B cause seasonal epidemics. Influenza A is the only type known to cause pandemics and is further divided into subtypes, such as the H1N1 and H3N2 viruses. Influenza type C infections differ from Types A and B as they generally cause mild illness and are not thought to cause widespread flu. Currently, the circulating influenza viruses are related to the pandemic 2009 H1N1 virus.

Each year, the seasonal influenza vaccine is designed to cover the three most common viruses expected to infect humans in the coming year. There are three kinds of flu that are important to understand³:

Influenza is a yearly concern for health professionals as it is a constantly changing, highly infectious and potentially deadly virus.⁵

The primary way that influenza viruses are transmitted is through droplet spread. When people infected with a flu virus cough, sneeze or talk, they produce droplets that can land in the mouth, eyes or noses of people nearby. Less commonly, a person might also get the flu through indirect contact: touching a contaminated surface or object and then touching their own mucous membranes (mouth, eyes or nose).⁶ Most healthy adults can infect others beginning one day before symptoms develop and up to five to seven days after becoming sick. Several groups are noted to have a high risk of transmitting influenza viruses, particularly school-age children (ages 5 to 19) and their parents.⁷ Healthcare workers, including fire fighters and other first responders, also have significant potential to transmit the virus through multiple patient contacts.

The flu is different from the common cold. Symptoms of the flu usually start suddenly and may include:

Although most healthy people recover from the flu within one week, certain groups are at high risk for serious complications. Older adults over 65, young children under 5, the immunocompromised, pregnant women, and people with chronic conditions are more likely to become seriously ill and possibly die from influenza.⁹ Complications from the flu include bacterial pneumonia, ear and sinus infections, and worsening of medical conditions such as congestive heart failure, asthma or diabetes., and sinus infections, and worsening of medical conditions such as congestive heart failure, asthma,

The time from when a person is exposed and infected with flu to when symptoms begin to show is about two days, but it can range from one to four days. A person may be able to spread the flu to someone else before becoming symptomatic. People with the flu are most contagious in the first three to four days after illness onset and symptoms present.

Influenza is a vaccine-preventable disease. The flu vaccine has been shown to reduce flu-related illnesses and the risk of serious complications. Ongoing research predicts the strains to be most common in the coming flu season. One influenza A H1N1, one influenza B H3N, and one or two Influenza B viruses are included in each season’s vaccines. About two weeks after vaccination, antibodies that protect against influenza virus infection develop in the body. The CDC and the Advisory Committee on Immunization Practices (ACIP) do not recommend one vaccine form over others.

An annual influenza vaccine is recommended for all fire fighters in NFPA 1582, Fire Department Infection Control Programs. Emergency responders need to be vaccinated with the seasonal flu vaccine every year. Currently, there are two kinds of flu vaccine available in the United States¹⁰:

Neither vaccine will cause a person to contract the virus; however, some individuals may experience mild flu-like symptoms from the body’s immune response.¹¹ The flu vaccine effectiveness varies from year to year but can reduce the risk of going to the doctor because of the flu by 40-60%.¹² It is important to note that seasonal flu vaccines do not protect against infection or illness caused by other viruses, such as COVID-19, that can also cause flu-like symptoms. Many other viruses besides influenza A or B can result in influenza-like illness that spread during flu season.

In addition to vaccination, you can help prevent the spread of influenza by: