There is no need to be overly rigid over this issue. According to the preferred view of eminent scholars, it is not haram to use vaccines containing minuscule ingredients such as gelatin or other forbidden elements.

Such ingredients used in medicines undergo a chemical transformation in such a way that it is wholly changed into another substance.

Thus it can be compared to alcohol turned into vinegar; while the former is haram, the latter is halal. Therefore, you need not worry about getting such vaccines as they are preventive measures.

Furthermore, standard rules are relaxed in case of treatments for saving the life is one of the priorities in Islam.

Allah Almighty knows best.