actually i just looked over the mmr ingredients and the only chemical i was unfamiliar with was sorbitol and neomycin.
vitamins, glucose, amino acids, sodium cloride, sodium phosphate, gelatine with removed double bonds to make the gelatine less prone to free radicals, should be all natural products. im guessing the amino acids and the salt is there as a buffer to keep the ph at a safe level, meaning if u take the ingredients separately it would kill you by changing the ph of ur blood. sodium phosphate is also in cocacola and most sodas.
sorbitol is natural
neomycin is an antibiotic to prevent the sample to be contaminated i guess...
about those cells, im sure u agree they are natural, and somehow the virus needs to be carried by cells...