Further if the jab is applied by a dilettante - so far all live views I did see, even from doctors, were done by dilettantes - then he does no check for a blood vessel hit.
These vaccines are intended for intramuscular injection, not intravenous. See below...
The manufacturer advises that it should not be injected intravascularly, subcutaneously or intradermally.(4) Intramuscular administration has the benefit of a better immune response to the vaccine, as the appropriate cells are present in the muscle tissue to initiate the immune response.(9) Subcutaneous injections can result in a local reaction and this is less likely intramuscularly, making it the preferred route.
Eta- this is a vaccine, not heroin.