A very intelligent close friend of mine has told me she does not vaccinate her children. She has done loads of research and believes her decision is well informed. Today she told me all about how diseases go through cycles and polio and smallpox were already on their way out when their respective vaccines were introduced. Hence, the vaccine was not responsible for their eradication. I don’t understand this. I’ve looked at the data and for the life of me I cannot understand how anyone could think that the sudden decrease in these illnesses could not be because of the vaccine. Is anyone here able to explain this logic to me please?