| transmission characteristics of the 2009 h1n1 influenza pandemic: comparison of 8 southern hemisphere countries. | while in northern hemisphere countries, the pandemic h1n1 virus (h1n1pdm) was introduced outside of the typical influenza season, southern hemisphere countries experienced a single wave of transmission during their 2009 winter season. this provides a unique opportunity to compare the spread of a single virus in different countries and study the factors influencing its transmission. here, we estimate and compare transmission characteristics of h1n1pdm for eight southern hemisphere countries/state ... | 2011 | 21909272 |