How Often Do I Need to Get the Flu Shot?
Unlike vaccines for other conditions, there is not a universal flu vaccine that provides lifelong immunity against all strains and subtypes of the flu. Part of the difficulty in creating a universal flu vaccine is the fact that the flu virus mutates very quickly. This means that last year’s vaccine may not be effective against this year’s virus. The vaccine is modified each year to include the specific strains of the influenza virus that are anticipated to be the most prevalent that year. The antibodies created by the vaccine also decrease with time, so the protection offered by the shot you got last fall will not be as strong this fall.
How Does the Flu Shot Work?
A flu shot works by using inactive or weakened versions of the virus to stimulate the body’s immune system into producing proteins called antibodies. If you are later exposed to the flu virus, these antibodies will recognize the virus and start to fight it. The vaccine itself cannot give you the flu. It is possible, however, to develop flu-like symptoms after getting a flu shot for one of the following reasons:
- You may experience a low-grade fever and mild muscle aches for a couple of days following the vaccination in response to your body producing the antibodies. This is normal and is not the same as getting the flu.
- It takes approximately two weeks for a flu shot to work. If you are exposed during that time, you could still develop the flu.
- You may still get the flu if you are exposed to a strain that was not included in the vaccine. Even if the vaccine does not completely protect you from the flu, your symptoms will likely be less severe than if you did not get the vaccine.
What Is In the Influenza Virus Vaccine?
Starting each February, the World Health Organization determines which versions of the flu virus are most likely to circulate over the following winter. Production of the vaccine normally starts in March. Most years, the vaccine will include two strains of the type A influenza virus and one or two strains of the type B influenza virus. The type A virus is the most serious and is largely responsible for widespread outbreaks. The type B virus is typically less severe and tends to cause smaller outbreaks. The exact ingredients in the vaccine can vary based on the type of vaccine and the manufacturer. If you have concerns about any possible vaccine ingredients, you should discuss your concerns with your MD Now provider before getting the vaccination. You should also let your provider know if you have an egg allergy or if you have had an allergic reaction to the flu shot in the past.
