Oct. 29, 2009 -- By the end of July, up to 5.7 million Americans -- 140 times the reported number -- had H1N1 swine flu.
As many as 21,000 were hospitalized by July 23, the CDC now estimates. This suggests that the current number of H1N1 swine flu - related hospitalizations -- just under 22,000 from the end of August to the middle of October -- is a vast underestimate.
When reporting numbers of hospitalizations and deaths, CDC officials have always noted that the data are a guide to the severity of the pandemic and not a precise tally.