Formerly, the pediatrician was faced with the problem of many diseases for which he could offer no preventive measures. Now he is faced with the problem in reverse: there are so many preventive vaccines available that he has difficulty scheduling them all. He may even have to "sell" the newer agents to some mothers (already wincing inwardly at the prospect of numerous painful shots to be administered on the baby's tender bottom!).
The principle of parsimony therefore ranks high among immunization guidelines favored by many pediatricians.