After COVID-19 vaccination, you may have some mild side effects. This is a normal sign that your body is building protection. The side effects from COVID-19 vaccination may feel like flu and might even affect your ability to do daily activities, but they should go away in a few days. Your arm may be sore, red, or warm to the touch. You may experience a low-grade fever, headache, and just a general feeling of “not yourself”. These are signs that your immune system is doing exactly what it is supposed to, which is produce an immune response for you to have protection against this disease.