This is really sad. These vaccines are supposed to protect the children, not harm them. I highly doubt, its the administration that resulted in the deaths. Most vaccines are given on the arm and other than some slight localized swelling, and maybe fever, nothing else is to be expected. Even when administered on the butt (which is rare in kids nowadays due to increased risk of mistake), worse case scenario would be severing a certain blood vessel (sciatic nerve) that could result in some limb paralysis but not necessarily death. Administration method is the least worrisome to the extent that lay people can be given medicine to go home and inject themselves or families are taught to do the same to prevent expensive hospital bills.
Something is either wrong with the medicine (who is making it, and with what? How is it stored, is it expired), or these kids are allergic to something used in making the drug or preserving it. For allergic reactions they should have medicine on hand to reverse the reaction and prevent the deaths. Its just not adding up....but then again in Kenya, nothing usually adds up. Its easier to blame the workers, but this is becoming too common now that something should be done about it before more kids die.