Identifying influential spreaders in complex networks SUPPLEMENTARY INFORMATION I. DATASETS In this study we have mainly focused on social networks, but our results can be extended to networks from practically any discipline. The datasets that were used in the paper and in this Supplementary Information are the following: a) Contact Network of Inpatients . We use records from Swedish hospitals [16] and estab- lish a link between two inpatients if they have both been hospitalized in the same quarters. We restrict the recording period to one week. All the data have been handled in a de- indentified form. There are 8622 inpatients in the largest component, with an average degree of around 35.1. b) IMDB actors in adult films . We have created a network of connections between actors who have co-starred in films, whose genre has been labeled by the Internet Movie Database [17] as ‘adult’. This network is a largely isolated sub-set of the original actor collabora- tion network. Additionally, all these films have been produced during the last few decades, rendering the network more focused in time. The largest component comprises 47719 ac- tors/actresses in 39397 films. The average degree of the network is 46.0. c) Email Contact Network . The network of email contacts is based on email messages sent and received at the Computer Sciences Department of University College London. The data have been collected in the time window between December 2006 and May 2007. Nodes in the network represent email accounts. We connect two email accounts with an undirected link in the case where at least two emails have been exchanged between the accounts (at least one email in each direction). There are 12701 nodes with an average degree of 3.2. d) LiveJournal.com . The network of friends in the LiveJournal community, as recorded in a 2008 snapshot. We only consider reciprocal links, i.e. when two members are in each other’s list of friends. There are 3453394 nodes in the largest component, and the average degree is 12.4. e) Cond-mat collaboration network . This is the network of collaborations between scien- tists that have posted reprints in the ‘cond-mat’ e-print archive, between 1995 and 2005. The 1