Available vaccines: inactivated quadrivalent: Afluria, Fluarix, Flublok FluLaval, Fluzone (intramuscular or intradermal), Flucelvax; inactivated trivalent: Afluria, Fluvirin, Fluad, Fluzone High-Dose, Flublok


Influenza (the flu) is a contagious respiratory illness due to the influenza virus. The virus infects the nose, throat, and lungs, causing a mild illness or a severe illness potentially requiring hospitalization and even resulting in death. Millions of people are diagnosed with the flu each year in the United States, hundreds of thousands are hospitalized, and thousands to tens of thousands of people die.

Common flu symptoms include fever or feeling feverish, cough, sore throat, runny or stuffy nose, body aches, headaches, fatigue, vomiting, and diarrhea. Some people may develop pneumonia, bronchitis, and ear or sinus infections as complications from the flu.

Antiviral drugs may be prescribed to individuals with the flu, but they have only been found effective in lessening symptoms and slightly reducing the duration of illness. However, in individuals at high risk for serious flu, antivirals may help in preventing flu complications and reduce the diagnosis to a milder course of illness.

Influenza Vaccine

Due to antigenic drift (small changes in influenza genes) and antigenic shift (abrupt, major change in neuraminidase proteins of the virus), our bodies’ antibodies no longer recognize the new strains of the flu, thus requiring a new vaccination every year to protect us.

The influenza vaccine should be administered prior to the start of flu activity in the community, ideally prior to the end of October. It takes approximately 2 weeks for the antibodies to develop after inoculation.

The nasal flu vaccine is not currently recommended for administration.

Who Should Get the Vaccine?

Anyone can get the flu, and the CDC recommends that everyone over the age of 6 months receive the flu vaccine each year. Those at increased risk of flu related complications include adults over age 65 years, pregnant women, young children, and individuals with certain chronic medical conditions (asthma, chronic obstructive pulmonary disease, diabetes, or heart disease).

Who Should NOT Get the Vaccine?

The flu vaccine should not be administered to anyone if they are under the age of 6 months, currently moderately to severely ill, have a history of Guillian-Barré syndrome within 6 weeks after receiving an influenza vaccine in the past, or if they had an allergic reaction to the vaccine in the past.

People with a severe allergy to eggs should be vaccinated in a medical setting and supervised by a healthcare provider who can recognize and manage a severe allergic reaction.

Side Effects

Adverse effects after receiving the influenza vaccine include pain and other injection-site reactions, headache, fever, tiredness, and myalgia, which many may attribute to the vaccine causing the flu.

Insurance Coverage

Medicare Part B normally covers one flu shot per flu season. Medicaid plans may or may not cover the vaccine. Most private health insurances cover the influenza vaccine.