Haha, microchip... she will be remote controlled by Beijing from now on, watch out! No, seriously speaking, I noticed this and asked the pharmacist giving the injection. This unusual round bandage that looks like it's made of concentric circles, and almost looks like the logo of the Target chain, serves two purposes.
The first is that it actually IS a target. The Covid vaccine needs to be given deep into the muscle instead of subcutaneously like other vaccines, from what I was told this is because the active ingredient is weaker than in other vaccines, and from within the muscle it is more readily transferred to the blood stream and hence can reach everywhere. For this they actually insert the entire length of the needle (looked like two inches, yuck), and they do it perpendicular to the skin surface as opposed to at a 45 degree angle like with other vaccines. But in this case, one has to make sure that it's really in an area of abundant muscle, and doesn't hit bone or the shoulder joint. This is a serious complication from vaccination, I never knew about it until DW who has a very slender build got a frozen shoulder, three months of pain, and the need for physical therapy from it a few years back. To do this reliably, the nurse first touches around to clearly identify the muscle, and then puts this little sticker where it's safest to inject so she doesn't forget in between.
The second reason is that the target-shaped sticker has the band aid part already in it, as the center of the target patch has some neat self-sealing material through which the needle is inserted. When blood seeps out after the shot, there's no need to clean it off and then place a band aid, the blood is automatically caught under the "target".
So it's all somewhat high tech and pretty cool.
