Flu Vaccine & Getting the Flu: What You Need to Know

It is impossible to get influenza (the flu) from the nasal or injectable influenza vaccines. However, it takes approximately two weeks after vaccination for antibodies that protect against influenza virus infection to develop in the body. Therefore, it is possible for someone to get the flu if they are exposed to the virus while in this two week window.

Additionally, the flu vaccine does not protect against other respiratory viruses, such as the rhinoviruses that cause the common cold, or parainfluenza viruses. So if a person gets sick after getting a flu vaccine, it may be because they have one of these other viruses.