Flu vaccines do not cause the flu. Flu shots are formulated with either an inactivated virus or no flu virus at all, making them non-infectious. The nasal spray flu vaccine contains a weakened live virus. Both types of vaccines stimulate the immune system to respond to flu viruses.
It’s important to note that you might still get sick shortly after receiving the vaccine. This is because it takes about two weeks for the antibodies from the vaccine to develop in the body and provide protection against the influenza virus. That’s why it’s recommended to get vaccinated promptly, in accordance with government recommendations in your region.