Responding to a question on our Facebook page, in this episode Graham and Ray talk about whether the flu vaccine is safe, why the formulation changes every year, what disease surveillance systems are, and introduce the epidemiological concepts, “bias” and “confounding.”

We mention that many modern vaccines don’t have the actual infective organism, but instead are made up of subunits of the organism which act as antigens. Here is a summary of which vaccines are typically made of actual organisms and which are made from inactive subunits:

Important links: