Antibodies are the body’s defenses against foreign objects like bacteria and viruses. After the body recognizes an invader, known as an antigen, antibodies attempt to neutralize it and recreate more antibodies. After an infection, antibodies remain, ready to fight the antigen should it enter the body again. Vaccinations expose people to an antigen to help the body develop antibodies to it.

Antigen drifts and shifts are types of mutations that viruses and other antigens undergo. In an antigen drift, the antigen changes just enough that antibodies struggle to attack it but still basically recognize it. In an antigen shift, the antigen’s gene coding changes, meaning the antibodies will no longer recognize the antigen, rendering them useless.

Blue was the surgeon general of the United States during the influenza pandemic. He was left off the National Research Council, as he was seen by other scientists as more of a politician. At first, Blue largely ignored the pandemic, but he eventually sent out posters and ads in newspapers offering advice on how to avoid getting influenza, though the ads were largely ineffective.