How long do COVID-19 booster side effects last? You probably experienced COVID-19 vaccine side effects fairly quickly when you had your initial injections. The same is true for COVID-19 vaccine booster shots: Most people notice side effects within the first 24 hours. The symptoms typically only last a day or two. Some people don't notice any side effects.
Can COVID-19 cause fatigue?
When your body is fighting off a viral infection like COVID-19, you may feel very tired and find it hard to focus. This is fatigue.
What does a booster shot do?
Typically, you would get a booster after the immunity from the initial dose(s) naturally starts to wane. The booster is designed to help people maintain their level of immunity for longer.