My best guess is that risk of blood clots will be added to a leaflet at some point.
Like when you have a medicine, and in the box, there is sometimes a long list of possible side effects, and some of them are written as a %.
Obviously, the covid vaccines are not like other vaccines that have been routinely given to people for the last 40 years or whatever. People have them, and there are leaflets of side effects and possible effects, and what to do if you get one.
Covid vaccines have only been given in the general population for 4 months or whatever, so what will be written and advised has not been completed yet.
My best guess, but dont necessarily go by me on this, things are still up in the air.
I am a bit surprised that countries[well European ones?] seem very skittish.