Influenza Pandemics: “The 1889–1890 flu pandemic, also known as Russian Flu, had a very high attack and mortality rate, causing around a million fatalities. Total mortality attributable to the 1918 Spanish Flu was probably around 40 million.  The “Asian Flu”, 1957–58. An H2N2 virus caused about 70,000 deaths in the United States.  First seen in China late Feb 1957 caused about 2 million deaths globally.  The “Hong Kong Flu”, 1968–69. An H3N2 caused about 34,000 deaths in the United States & killed approximately one million people worldwide .  In the spring of 2009, a novel influenza A (H1N1) virus emerged. It was detected first in the United States and spread quickly across the United States and the world. This new H1N1 virus contained a unique combination of influenza genes not previously identified in animals or people. This virus was designated as influenza A (H1N1)pdm09 virus. The (H1N1)pdm09 virus was very different from H1N1 viruses that were circulating at that time; vaccination with seasonal flu vaccines thus offered little cross-protection against (H1N1)pdm09 virus infection. While a monovalent (H1N1)pdm09 vaccine was produced, it was not available in large quantities until late November, which was after the peak of illness during the second wave had come and gone in the United States. From April 12, 2009 to April 10, 2010, CDC estimated that there were 60.8 million cases (range: 43.3-89.3 million), 274,304 hospitalizations (195,086-402,719), and 12,469 deaths (8868-18,306) in the United States due to the (H1N1)pdm09 virus.* CDC estimated that between 151,700 and 575,400 people worldwide died from 2009 H1N1 virus infection during the first year the virus circulated.”

Centers for Disease Control and Prevention