The article discusses the importance of international sharing of virus data for global health, highlighting the challenges in achieving this. It presents the first study of the Global Initiative on Sharing All Influenza Data (GISAID), which has successfully promoted the sharing of influenza virus data. GISAID has made five key contributions to global health: (1) maintaining the most complete repository of high-quality influenza data; (2) facilitating the rapid sharing of potentially pandemic virus information during outbreaks; (3) supporting the World Health Organization's seasonal flu vaccine strain selection process; (4) developing informal mechanisms for conflict resolution around virus data sharing; and (5) building trust with countries key to pandemic preparedness. The article also discusses the challenges in sharing virus data, including scientists' concerns about recognition, governments' fears of economic repercussions, and the need for sustainable funding. GISAID's innovative data access agreement and its governance structure have helped overcome these challenges, enabling the timely sharing of virus data. The initiative has also contributed to global health security by promoting rapid data sharing during outbreaks, such as the 2009 H1N1 pandemic and the 2013 H7N9 outbreak. GISAID's role in the selection of seasonal flu vaccine strains is also highlighted, as it is routinely used by WHO Collaborating Centres in the biannual process of selecting viruses for the seasonal flu vaccine. The article concludes that GISAID has been successful in meeting its aims and objectives, and its innovative approach to data sharing serves as a useful blueprint for managing other diseases and global challenges requiring the international sharing of sensitive data.The article discusses the importance of international sharing of virus data for global health, highlighting the challenges in achieving this. It presents the first study of the Global Initiative on Sharing All Influenza Data (GISAID), which has successfully promoted the sharing of influenza virus data. GISAID has made five key contributions to global health: (1) maintaining the most complete repository of high-quality influenza data; (2) facilitating the rapid sharing of potentially pandemic virus information during outbreaks; (3) supporting the World Health Organization's seasonal flu vaccine strain selection process; (4) developing informal mechanisms for conflict resolution around virus data sharing; and (5) building trust with countries key to pandemic preparedness. The article also discusses the challenges in sharing virus data, including scientists' concerns about recognition, governments' fears of economic repercussions, and the need for sustainable funding. GISAID's innovative data access agreement and its governance structure have helped overcome these challenges, enabling the timely sharing of virus data. The initiative has also contributed to global health security by promoting rapid data sharing during outbreaks, such as the 2009 H1N1 pandemic and the 2013 H7N9 outbreak. GISAID's role in the selection of seasonal flu vaccine strains is also highlighted, as it is routinely used by WHO Collaborating Centres in the biannual process of selecting viruses for the seasonal flu vaccine. The article concludes that GISAID has been successful in meeting its aims and objectives, and its innovative approach to data sharing serves as a useful blueprint for managing other diseases and global challenges requiring the international sharing of sensitive data.