1.   An influenza pandemic.

2.   Her concern with public health could be traced to her grade-school days, when the influenza pandemic at the end of World War I killed many Navajos.

3.   Our world has been swept by three influenza pandemics in this century.

4.   Recently, health experts from throughout the United States gathered in Atlanta to develop plans in the event of a severe influenza pandemic.

5.   There have been three influenza pandemics this century.