The Atlantic on February 2nd posted a good article "The Second COVID-19 Shot Is a Rude Reawakening for Immune Cells" by Katherine J. Wu.
"Side effects are just a sign that protection is kicking in as it should".
For more information click on the image or go to https://www.theatlantic.com/health/archive/2021/02/second-vaccine-side-effects/617892/