Some children became crippled due to such unsafe practices.

In fact not only vaccines, but also other injections can cause such injury. It seems also that antibody response is lower when injection is made into the gluteal region. So almost everyone recommends that buttocks should be avoided for intramuscular injections in children.

In addition to abovementioned, only few nurses and doctors aspirate after insertion of the needle. So it is not clear what type of injection is done - intramuscular or intravenous. If vaccine follows IV route than we should expect that the effectiveness of the intervention will be low. Safety also could be a problem. This is true not only for vaccines but also for other injections, except Penicillin G benzathine and few others.