The estimated within - school reproduction rate, or number of new infections caused by an infected person, was 3.3, comparable to school - based outbreaks of other influenza strains. (jhsph.edu)
In 2010, the estimated number of new infections in the United States was only 17,000. (sciencemag.org)
In Eastern Europe and Central Asia, which has a relatively recent epidemic, the annual number of new infections was 70 % higher than 2 years ago. (sciencemag.org)