In Senate subcommittee hearings in 1977, the U.S. Army revealed that weeks before Mr. Nevin sickened and died, the Army had staged a mock biological attack on San Francisco, secretly spraying the city with Serratia and other agents thought to be harmless.

Of Microbes and Mock Attacks - In 1950s, The Military Sprayed Germs on U.S. Cities

If this doesn’t get you in the mood to watch Contagion and Panic in the Streets, I don’t know what will.