1957–1958 influenza pandemic

The 1957-58 influenza pandemic, also called Asian flu was a time when many people caught H2N2 influenza A and became sick. Westerners first learned about this influenza when it was in Singapore. It killed 1.1 million people.
The influenza virus that caused the pandemic had an HA antigen and NA antigen that scientists had never seen before, so they named it "H2N2."
The 1957 influenza pandemic was the first time scientists truly studied how influenza could move through large groups of people who had not had vaccines that worked against it yet.