The Flu: What You Need to Know

kim tranThe arrival of fall brings coughs, runny noses and sneezes in offices, schools and homes in many parts of the country. Fall is also the start of flu season. That means it's a good time to get your annual flu immunization to help boost your protection against influenza (flu) viruses.

Flu seasons are unpredictable, so protecting you and your family from infection is critical. Everyone is at risk for catching the flu. Up to 20% of people in the United States get the flu each year, and US hospitals admit more than 200,000 people annually for flu-related complications.

As a pharmacist, I answer many questions about vaccinations during flu season. Here are the most common questions:

Q: How old do you have to be to get the flu vaccine?

A: If you are 6 months or older, you are old enough for the flu vaccine. In fact, the Centers for Disease Control and Prevention (CDC) recommends that everyone 6 months and older get vaccinated. Vaccines are designed for different age groups, ranging from youngchildren to pregnant women to those aged 65 years and older. Talk to your pharmacist to see what flu vaccine is best for you.

Q: Will the flu shot interfere with other shots that my child has received?

A: The flu vaccine does not interfere with the immune response to other vaccines. Flu vaccines (with the exception of the live attenuated nasal spray flu vaccine) contain either inactivated viruses that do not interfere with other inactivated or live vaccines, or they contain no viruses at all, which is the case for recombinant influenza vaccines as they are developed using DNA technology.

Although the nasal spray flu vaccine does contain live viruses, the viruses are weakened and cannot cause flu illness. This option should not be administered to people with certain chronic health conditions because the safety of this vaccine in people with those conditions has not been established.

Q: Are there specific flu vaccine considerations for children?

A: Children aged 6 months to 8 years may require two doses of flu vaccine. The first dose primes the immune system and should be given as soon as the vaccine becomes available. The second dose provides immune protection and should be given at least 28 days after the first dose. Children who only get one dose but need two doses can have reduced or no protection from a single dose of flu vaccine. If your child needs the two doses, begin the process early to ensure your child is protected before influenza starts circulating in your community.

Q: How long does the flu vaccine last? Will it wear out if I get it too early in the season?

A: Immunity lasts through a full season for most people, though immunity obtained from the flu vaccine can vary by person. In fact, the CDC recommends obtaining your flu vaccine soon after the vaccine becomes available, by October if possible. However, as long as flu viruses are circulating it is not too late to get vaccinated, even in January or later.

Q: Does the flu vaccine really work?

A: A flu vaccine's ability to protect a person from infection depends on varying factors. These include personal characteristics, such as your age and health, and the similarity or match between the viruses in the vaccine and those in circulation. Depending on how well-matched the vaccine is to circulating viruses for that flu season, there can be substantial benefits from vaccination in terms of preventing flu illness or making your illness milder if you do get sick.

Q: Can the flu vaccine give me the flu?

A: No. The majority of flu vaccines are made in one of two ways: with flu vaccine viruses that have been inactivated and are not infectious, or with no flu vaccine virus at all. However, because it takes up to two weeks to obtain full immunity, it is possible to be exposed to influenza during this time and become infected with the flu. Additionally, the flu vaccine only protects against specific strains of influenza viruses.

Although the nasal spray flu vaccine does contain live viruses, the viruses are weakened and 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.

Q: What are the risks associated with a flu vaccination?

A: The risk of a flu vaccine causing serious harm is extremely small. Almost all people who get a flu vaccine experience no serious problems. The most common side effect of the flu vaccine is soreness at the site of injection. The most common side effect associated with the nasal vaccine is a mild runny nose and congestion. Like any vaccine or medicine, the flu vaccine may rarely cause serious problems, such as severe allergic reactions. If you experience a severe reaction, seek immediate treatment.

Q: Do I have to go to my physician to be vaccinated?

A: While you can certainly get a flu vaccine in your physician's office, many pharmacies and other locations offer this service without requiring an appointment. Pharmacists are specifically licensed to administer vaccines and can answer questions about the products.

Q: What types of flu shots are available?

A: Traditional flu vaccines protect against three flu viruses and are called trivalent vaccines. In addition, some flu vaccines are made to protect against four flu viruses. These are called quadrivalent vaccines.

According to the CDC, the following types of flu shots are available. The CDC does not recommend any one vaccine over another. Availability will vary by region. As always, talk to your healthcare provider about which option is best for you or your family.

flu vaccine chart

To learn more about the flu and options to help protect you and your family, please visit


CDC. "Key Facts about Influenza (Flu) & Flu Vaccine." Seasonal Influenza (Flu) 2015. Available at: Accessed September 2015.

CDC. "Seasonal Influenza Q&A." Seasonal Influenza (Flu) 2015. Available at: Accessed September 2015.

CDC. "Key Facts about Seasonal Flu Vaccine." Seasonal Influenza (Flu) 2015. Available at: Accessed July 2015.

CDC. "Influenza Vaccination: A Summary for Clinicians." Vaccination 2015. Available at: Accessed September 2015.

CDC. "Seasonal Flu Shot." Types of Flu Vaccine 2014. Available at: Accessed September 2015.

CDC. "How Influenza (Flu) Vaccines are made." Prevention – Flu Vaccine 2015. Available at: Accessed September 2015.

CDC. "Live Attenuated Influenza Vaccine [LAIV] (The Nasal Spray Flu Vaccine)." Types of Flu Vaccine 2015. Available at: Accessed September 2015.

CDC. "Misconceptions about Seasonal Flu and Flu Vaccines." Flu Vaccines & Preventing Flu Illness 2015.Available at: Accessed September 2015.

CDC. "Vaccine Effectiveness – How Well Does the Flu Vaccine Work?" Flu Vaccines & Preventing Flu Illness 2015. Available at: Accessed September 2015.

CDC. "What You Should Know for the 2015-2016 Influenza Season." 2015-2016 Flu Season 2015. Available at: Accessed September 2015.

New York State Department of Health. "Pharmacists as Immunizers." Information for Providers 2015. Available at: . Accessed September 2015.

FDA. "Thimerosal in Vaccines Questions and Answers." Vaccines 2015. Available at: Accessed September 2015.

CDC. Provider Information: Influenza VISs. 2014. Available at: Accessed September 2015.


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