Duke infectious disease expert Cameron Wolfe, MD, responds to common questions about the flu vaccine.

Can someone get the flu by getting the flu shot?

The flu injection cannot transmit the flu or make you more susceptible to getting the flu. It contains no flu virus. 

Cameron Wolfe, MDWhy do some people say they always get sick after getting the flu shot?

This may be true, but for a very small number of people.

The vaccine is quite good at building your immunity, so some people with a robust immune system will respond more vigorously to the vaccine building their immunity, but feeling a little worse while that occurs.

A sore shoulder, low-grade temperatures, and mild aches are possible for about 5 to 10 percent of the adult population.

Remember, it’s building your immunity, so it’s a protective response. The vaccine will not give you the flu.

Can the flu shot cause Guillain-Barre syndrome (GBS)?

Fortunately this condition, which occurs naturally every year in the United States, is extremely rare -- perhaps one case per 100,000 per year.

If you have had this illness before, you should discuss the flu vaccination with your health care provider. Recent studies of influenza vaccination have shown the risk of GBS to be minimal.

If I get vaccinated, won’t that prevent me getting natural immunity?

This is true. Sadly, however, the only way to get natural immunity to influenza, which changes every year, is to either catch the flu and get sick from it or to be vaccinated.

By having the flu, you put yourself and others at risk. The immunity generated from the vaccine is exactly the same as from the virus itself.

Why are you vaccinating people now, when flu season doesn’t start until the winter?

Because the vaccine takes at least a couple of weeks to have its full benefit, it is important to get the vaccine before influenza starts to circulate.

If I take the vaccine now, will I still be protected by the end of the season?

Yes. It was originally thought that waiting until the last minute was better, but the current flu vaccines have protection throughout the entire season with minimal waning.

Why do healthy people need to get the flu shot?

In short, to protect those who are not as fortunate. It is true that the people at greatest risk for influenza are those who have chronic illness, the elderly, or the very young. But, even if you are well, you may be in contact with others who are at greater risk than you.

Have more questions about the flu vaccine? Visit dukehealth.org/flu. Together, we can stop the flu.