The surprise pandemic of 1918 shook Americans' confidence in the medical establishment that had previously found vaccines for other lethal diseases like smallpox and typhoid. People tried everything to avoid getting the virus--from gargling with mouthwash to wearing masks--but it was not until years after the pandemic was over that scientists made any real breakthroughs. See how the flu epidemic spread through the U.S., with this gallery from American Experience: "Influenza 1918."