The1889–1890 flu pandemic(October 1889 – December 1890, with recurrences March – June 1891, November 1891 – June 1892, winter 1893–1894 and early 1895) was a deadly influenza pandemic that killed about 1 million people worldwide. The outbreak was dubbed “Asiatic flu” or “Russian flu” (not to be confused with the 1977–1978 epidemic caused by Influenza A/USSR/90/77 H1N1, which was also called Russian flu). For some time the virus strain responsible was conjectured (but not proven) to be Influenza A virus subtype H2N2.^[3][4]More recently, the strain was asserted to be Influenza A virus subtype H3N8.^[5]

Modern transport infrastructure assisted the spread of the 1889 influenza. The 19 largest European countries, including theRussian Empire, had 202,887 km of railroads and transatlantic travel by boat took less than six days (not significantly different than current travel time by air, given the time scale of the global spread of a pandemic).^[5]

The pandemic was first recorded inSaint Petersburg, Russia in December 1889. In four months it had spread throughout the Northern Hemisphere. Deaths peaked in Saint Petersburg on December 1, 1889, and in the United States during the week of January 12, 1890. The median time between the first reported case and peak mortality was five weeks.^[5]

Researchers have tried for many years to identify the subtypes of Influenza A responsible for the 1889–1890, 1898–1900 and1918epidemics. Initially, this work was primarily based on “seroarcheology”—the detection of antibodies to influenza infection in the sera of elderly people—and it was thought that the 1889–1890 pandemic was caused by Influenza A subtype H2, the 1898–1900 epidemic by subtype H3, and the 1918 pandemic by subtype H1.^[7]With the confirmation of H1N1 as the cause of the1918 flu pandemicfollowing identification of H1N1 antibodies in exhumed corpses,^[8]reanalysis of seroarcheological data has indicated that Influenza A subtype H3 (possibly the H3N8 subtype), is the most likely cause for the 1889–1890 pandemic.^[5][9]