wave

The worldwide influenza outbreak of 1918–19 was a medical catastrophe,
causing the deaths of around 50 million people. There is evidence however that the
major wave, in November 1918, was not part of the pandemic that started in the
summer of 1918. The virus responsible for the major wave has been isolated but the
structural features responsible for its severity remain incompletely understood. In
1918–19 influenza was an infection so little understood that the government was