It covers the period from late-August 1939, immediately prior to the outbreak of World War II, to October 1940, by which time the Blitz had begun and much of Europe was occupied by the Germans.

FORBES: Magazine Article

Mexican authorities believe the virus's most active period in Mexico was between April 23 and April 28, and Mexican Health Secretary Jose Cordova described the outbreak as being in decline in his country.

CNN: Confirmed cases of H1N1 virus approach 900