What is influenza (also called flu)?
The flu is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and lungs. It can cause mild to severe illness, and at times can lead to death. The best way to prevent the flu is by getting a flu vaccine each year.
How do flu vaccines work?
Flu vaccines cause antibodies to develop in the body about two weeks after vaccination. These antibodies provide protection against infection with the viruses that are in the vaccine.
The seasonal flu vaccine protects against the influenza viruses that research indicates will be most common during the upcoming season. Traditional flu vaccines (called trivalent vaccines) are made to protect against three flu viruses; an influenza A (H1N1) virus, an influenza A (H3N2) virus, and an influenza B virus. In addition, this season, there are flu vaccines made to protect against four flu viruses (called “quadrivalent” vaccines). These vaccines protect against the same viruses as the trivalent vaccine as well as an additional B virus.
Who should get vaccinated this season?
When should I get vaccinated?
Flu vaccination should begin soon after vaccine becomes available, ideally by October. However, as long as flu viruses are circulating,vaccination should continue to be offered throughout the flu season, even in January or later. While seasonal influenza outbreaks can happen as early as October, most of the time influenza activity peaks in January or later. Since it takes about two weeks after vaccination for antibodies to develop in the body that protect against influenza virus infection, it is best that people get vaccinated so they are protected before influenza begins spreading in their community.
Special Consideration Regarding Egg Allergy:
People who have ever had a severe allergic reaction to eggs
may be advised not to get vaccinated. People who have had a mild reaction to egg—that is, one which only involved hives—may receive a flu shot with additional precautions. Make sure your health care provider knows about any allergic reactions. Most, but not all, types of flu vaccine contain small amount of egg.
Where can I get a flu vaccine?
Flu vaccines are offered in many locations, including doctor’s offices, clinics, health departments, pharmacies and college health centers, as well as by many employers, and even in some schools.
Even if you don’t have a regular doctor or nurse, you can get a flu vaccine somewhere else, like a health department, pharmacy, urgent care clinic, and often your school, college health center, or work.
Can the flu vaccine give me the flu?
No, a flu vaccine cannot cause flu illness. Flu vaccines that are administered with a needle are currently made in two ways: the vaccine is made either with a) flu vaccine viruses that have been ‘inactivated’ and are therefore not infectious, or b) with no flu vaccine viruses at all (which is the case for recombinant influenza vaccine). The nasal spray flu vaccine does contain live viruses. However, the viruses are attenuated (weakened), and therefore cannot cause flu illness. The weakened viruses are cold-adapted, which means they are designed to only cause infection at the cooler temperatures found within the nose. The viruses cannot infect the lungs or other areas where warmer temperatures exist.
Different side effects can be associated with the flu shot and nasal spray flu vaccines. These side effects are mild and short-lasting, especially when compared to symptoms of influenza infection.
The flu shot: The viruses in the flu shot are killed (inactivated), so you cannot get the flu from a flu shot. Some minor side effects that could occur are:
- Soreness, redness, or swelling where the shot was given
- Fever (low grade)
The nasal spray: The viruses in the nasal spray vaccine are weakened and do not cause severe symptoms often associated with influenza illness. In children, side effects from the nasal spray can include:
- Runny nose
- Muscle aches
In adults, side effects from the nasal spray vaccine can include
- Runny nose
- Sore throat
If these problems occur, they begin soon after vaccination and are mild and short-lived. Almost all people who receive influenza vaccine have no serious problems from it. However, on rare occasions, flu vaccination can cause serious problems, such as severe allergic reactions. People who think that they have been injured by the flu shot can file a claim for compensation from the National Vaccine Injury Compensation Program (VICP).
More information about the safety of flu vaccines is available at Influenza Vaccine Safety.
• Misconceptions about Seasonal Influenza & Influenza Vaccines
• Vaccine Effectiveness – How Well Does the Flu Vaccine Work?