Can receiving the flu vaccine cause you to contract influenza?

Can receiving the flu vaccine cause you to contract influenza?

• A. Yes, vaccines can sometimes cause influenza infection.
• B. No, the vaccine cannot give you the flu because it contains inactivated or weakened viruses that cannot cause infection.
• C. Only if you are exposed to the virus at the same time as vaccination.
• D. The vaccine always causes a mild case of flu-like illness.

Answer: (B)

Receiving the flu vaccine does not cause influenza. The vaccines are made with either inactivated (killed) viruses or, in some formulations, proteins that stimulate the immune system, or with a live virus that is weakened so it cannot cause illness in healthy people. Because there is no fully infectious influenza virus being introduced, you cannot contract influenza from the shot itself. You might experience a mild immune response, like soreness at the injection site or a low fever, or you could coincidentally pick up a different respiratory virus around the same time, but that isn’t influenza caused by the vaccine. If you do get influenza after vaccination, it’s usually because exposure occurred before immunity developed or the circulating strain isn’t fully matched by the vaccine.

Receiving the flu vaccine does not cause influenza. The vaccines are made with either inactivated (killed) viruses or, in some formulations, proteins that stimulate the immune system, or with a live virus that is weakened so it cannot cause illness in healthy people. Because there is no fully infectious influenza virus being introduced, you cannot contract influenza from the shot itself. You might experience a mild immune response, like soreness at the injection site or a low fever, or you could coincidentally pick up a different respiratory virus around the same time, but that isn’t influenza caused by the vaccine. If you do get influenza after vaccination, it’s usually because exposure occurred before immunity developed or the circulating strain isn’t fully matched by the vaccine.