Any vaccine can cause a reaction that is in the mild sense. People need to understand that vaccines are Made up of either dead virus or bacteria, Mutated but live weakened Viruses, or a piece or fragment of a virus or bacteria. The 1st and last cannot give you the infection the 2nd could give you a mild one. The important thing is that you have an Immune response That means your body sees the foreign object of whatever type and reacts to it and starts making antibodies And it is the antibodies that save you from the worst infection that the vaccine is for. Now while your immune system is working to make antibodies you sometimes go through a flu like symptom pattern for 24 to 48 hours, That is not you getting sick that is your body's response to any foreign particle while it attacks the foreign particle. People feel fatigue, Have arm pain, Feel nauseated sometimes even vomit, Have mild fevers, And general feeling of unwellness. It always is recommended after having a vaccine to rest that night , eat a good dinner, Have lots of hydration, No strenuous exercise or heavy lifting, And pampering yourself is not a bad idea. Your body's working on the inside hard it doesn't need you to work so much on the outside Is that day. Most people don't have to have a note to go to work if they're post vaccine with feeling unwell they just bring in the evidence they have the shot. Most post vaccine fevers And body aches are treated well with Tylenol Or motrin