Does the flu jab give you flu symptoms? Everything you need to know about the vaccine

“You can’t get flu from the flu jab, because the injection doesn’t contain any active virus,” Day told medical website Patient.info.

“It just allows the body’s immune system to recognise the virus so it can fight it later, if you are exposed to it.

“If you feel ‘fluey’ after the jab, you might have caught a different virus, or you might have been exposed to the flu virus before the vaccine had a chance to start working – which is why it’s important to get it in the autumn, before the flu season starts.

“We know the flu jab works, but it’s not 100 percent guaranteed to prevent every case of flu. However, if you do catch flu after having the jab, it’s likely to be much milder and quicker than it would otherwise have been.”