Published on September 13, 2017

Q&A: Why is the Flu Shot So Important?

Why is the Flu Shot So Important

Q: Why is the flu shot so important?

Influenza is a contagious respiratory virus that can cause mild to severe respiratory illness, and at times even death. Most deaths in NC from the 2016-2017 influenza season were people who did not get vaccinated and had several other health problems such as emphysema, COPD, diabetes, heart disease, and obesity.

The best way to protect yourself from the flu is to get vaccinated. The vaccine is recommended for everyone 6 months and older. Although, it may not completely prevent a person from getting the flu, it will minimize the days and severity of illness.

Q: When is the best time to get a flu shot?

The Centers for Disease Control and Prevention (CDC) recommends getting your injectable influenza vaccine by the end of October. Some people are concerned that they may be getting the vaccine too early in the flu season. The flu season usually starts in October and it peaks in January/February. It is often difficult to predict if it will be as prolonged in the community as it was the previous year. Since it takes roughly two weeks for your immune system to mount a response to the vaccine, it is important to receive the vaccine once it becomes available.

Q: How long does the flu vaccine stay in your system?

The vaccine is thought to be protective for one year. Over that time we start to see a decrease in antibody levels (immune response). Also, there is typically a new circulating strain of influenza virus from year to year.

As we age, our immunity to influenza vaccines wanes over time quicker than a younger population during one flu season. To compensate for this, there are high-dose vaccine formulation to produce a higher immune response in those over age 65. Studies show that the high-dose vaccine for the elderly minimized the number of hospitalizations related to influenza.

Q: Will the shot become less effective as time passes?

The vaccine becomes less effective towards the end of 12 months for a few reasons. First, the antibody response to influenza starts decreasing, however current studies do not suggest any benefit to getting another flu vaccine 6 months from the first vaccination as a booster. The exception to this is children from the ages of 6-35 months. They will need 2 doses of influenza vaccine.

Secondly, circulating influenza strains that are not included the vaccine may also impact the vaccine effectiveness. For example, in the flu season of 2016-2017, the vaccine was thought to only be 50% effective because the predominant circulating influenza strain was excluded in the vaccine. However, this has been taken into account for the upcoming flu vaccine for 2017-2018.

Q: What population most needs the flu shot?

In general, we recommend flu vaccine for everyone over 6 months of age. Certain populations are at more risk for complications associated to influenza, and thus would benefit most from being vaccinated. they include:

  • those over 65
  • the very young
  • pregnant women
  • people with other medical problems such as immunocompromised due to cancer or medications, COPD, emphysema, asthma, diabetes mellitus, heart disease, obesity and HIV

Q: If I have the flu, does that mean I don't need the vaccine?

Since there are many strains of influenza that can circulate in a given year, it is still important to get the vaccine in order to protect oneself from other circulating strains.

If you think you may have signs and symptoms of having influenza, please visit your primary care provider to be evaluated for need of anti-viral treatment.

The signs and symptoms of an influenza like illness include fever, cough, sore throat, runny nose, body aches, headache, chills, fatigue, and sometimes diarrhea and vomiting.

It is also important to consider not going to work if you have these symptoms and may have influenza, since you may place others at risk for contracting the virus.

Stop the flu in tracks by getting vaccinated. Remember to practice respiratory hygiene (cover your cough by wearing a mask or coughing into your upper arm instead of your hands) as well as proper hand hygiene.

About the Author

Dr. Cynthia Snider

Cynthia B. Snider, MD, MPH Infectious Disease, Internal Medicine at the Regional Center for Infectious Disease