What has changed since the Great Flu Pandemic of 1918–19 that affects your answer?

The Great Influenza Pandemic of 1918–1919 spread worldwide and occurred in waves, resulting in the deaths of nearly five percent of the world population. Do you think the United States is vulnerable to a flu pandemic today? Why, or why not? What has changed since the Great Flu Pandemic of 1918–19 that affects your answer? Give specific examples to support your perspective.