I got the first Pfizer shot on April 23. The immediate side effect was arm soreness that lasted two or three days. Not horrible, but very noticeable when I moved my arm.
Saturday, the 30th, I started to feel unwell, then went downhill fast to the point where I was shaking so hard with chills I thought I might pull a muscle. I was sick and fevery until this morning. I went for a Covid test, which came back negative.
So who knows? Seven days seems like a long time for a delayed vaccine reaction, so maybe I had something else. It’s also possible that I had Covid, but the vaccine kept the levels low enough that the test was a false negative. Apparently that happens sometimes.
So… it’s a mystery. But I’m offering it up as a data point in case others had a similar experience.