When I had an appointment with my doctor in August, he recommended that I get the flu shot that day, but wait until a COVID booster that addresses the recent Omnicron variants was out before getting that.
Got my flu shot on August 25th. Afterwards, it seemed like I actually felt better (maybe because all my test results came back normal). However, that night I slept very poorly, and the next day I had a lot of nausea and shakiness (part of this was due to klonopin tapering, but I think the vaccine made it worse). During the following days, I felt about the same as most days during that part of the taper.
Got my COVID booster (Pfeizer) on October 14. Note that the two times I had previously gotten this shot (the 2nd vaccine of the 2-vaccine series back in early 2021, and a booster in November 2022), I had a fairly bad headache the next day, along with a sore arm. At the times I got the previous COVID shots, I was not taking any benzos and was in general in good health (physical and mental). The day of the COVID shot this time, I did not notice any symptoms other than my arm becoming slightly sore. I didn't notice any significant change from my normal (post-withdrawal) sleep that night. Yesterday (day after vaccine), my arm was fairly sore (a bit uncomfortable but certainly not intolerable). A very slight headache - it was hardly noticeable. I thought I felt some slight chills during the evening, but nothing severe and not sure if it was just the temperature in the room. Sleep last night was normal (for this point post-withdrawal), and today most of the soreness in my arm is gone. Although I am experiencing some depression, I attribute it to klonopin withdrawal at this point (I don't think the vaccine worsened it).
