I just looked at the NHS site for the MMR vaccine and it says
Maybe there are more worst case scenarios for children who get one of the M M R viruses than for children who get covid, but the side effects risk is apparently much higher too, and the vaccine is accepted.www.nhs.uk wrote:There's a small chance of having a seizure (fit) 6 to 11 days after the MMR vaccine. This can be caused by having a high temperature in response to the measles vaccine virus.
It may sound alarming but having a seizure after the MMR vaccine is rare. They happen in about 1 in every 1,000 doses given.
(In looking this up I see the UK has apparently eliminated rubella, but not measles or mumps).
Re. non-validated vaccines, people coming to live in France having received any "unofficial" vaccine get an antibody test and then either one or two approved doses. I've heard anecdotally that the Sinopharm vaccine shows no antibodies on people being tested 6 months later.