World Science Festival, May 22, 2012
Our brains are not the only places where we can store memories. Each time a new pathogen invades our bodies, our immune cells have an opportunity to recognize it by some feature, usually some distinctive cleft or spike of a protein on its surface. After our bodies defeat the infection, some immune cells are tasked with keeping the memory of that feature alive for years. If that same pathogen returns for a second attack, our bodies can launch a far faster counterattack.
We can tutor our immune systems with vaccines. Depending on the disease they protect against, vaccines may contain dead viruses, protein fragments, or some other substance derived from a pathogen.