The second group included travelers diagnosed with H1N1pdm09 while in an exposure country and whose exposures were attributed to either their country of residence before travel or to a prior exposure country on the same trip. No differences between the groups were observed for any analysis, so pooled data is shown. Cases with uncertain country of exposure were excluded from some analyses. To investigate the association between transmission intensity in a country and the time of H1N1pdm09 exportation from MAPK inhibitor that country, we

classified the 22 countries into three different pandemic intervals by using the classification scheme available from the US Department of Health and Human Services (Figure 1)[5] as described in the following text. Definitions[5] of the observed three pandemic intervals are given as follows: Initiation Interval, this interval begins with the identification and laboratory confirmation of the first human case due to pandemic influenza virus in the [Country]; Acceleration Interval, this interval begins in a [Country] when public health officials have identified that containment efforts have

not succeeded, onward transmission is occurring, or there are two or more laboratory-confirmed cases in the [Country] that are not epidemiologically linked to any previous case; and Peak Transmission Interval, this interval encompasses the time when there is extensive transmission in the community

and the [Country] has reached its greatest number of check details newly identified cases. We used available official country-specific surveillance data and web-based reports to define the pandemic interval (transmission intensity) for each country (see text below). For most countries, Wilson disease protein the pandemic interval was assessed at the time of exportation (defined as the clinic visit date of the first GeoSentinel case for that country). For countries whose clinic visit date of the first GeoSentinel case was after June 30, 2009, the transmission intensity on June 30, 2009, was used to assess the pandemic interval in each country. By June 30, 2009, the pandemic strain had been circulating for nearly 2 months and the WHO had officially reported a case in each of the 22 countries of interest, so that transmission intensity on that date is an indicator of overall country status in the face of the fully established worldwide pandemic. Even if the first exported case from a country was much later during a subsequent wave, that country would still be counted as an initiation phase country for the purpose of the statistical analysis performed. Countries were classified into the following pandemic intervals: initiation (low-transmission intensity), acceleration (moderate-transmission intensity), and peak transmission (high-transmission intensity).