Transparency refers to an environment in which the objectives of policy, its legal, institutional, and economic framework, policy decisions and their rationale, data and information related to monetary and financial policies, and the terms of agencies‘ accountability, are provided to the public in a comprehensible, accessible, and timely manner. 
There are two inter-related aspects of transparency during an outbreak. One refers to the quality of communication, communication should be factually accurate, timely and easily understood. The second aspect relates to building trust by sharing information with interested members of the public and partners so they can better understand decision-making processes involved in outbreak management. These two aspects are captured in the following definition.
Transparency in outbreak communication means that:
- At-risk and interested publics are informed in an accurate, accessible and timely manner about an actual or potential health risk, including behaviors they should adopt to avoid disease and to control infection spread, and control measures undertaken by public health authorities;
- Public health stakeholders not directly involved in public health emergency management decisions are given timely access to the information used to inform outbreak and emergency management planning, policy and control decisions, as well as information about relevant decision-making processes and outcomes.
Transparency International 
Characteristic of governments, companies, organizations and individuals of being open in the clear disclosure of information, rules, plans, processes and actions.
As a principle, public officials, civil servants, the managers and directors of companies and organizations, and board trustees have a duty to act visibly, predictably and understandably to promote participation and accountability and allow third parties to easily perceive what actions are being performed.
"Transparency initiatives in service delivery are relatively easy to define: any attempts (by states or citizens) to place information or processes that were previously opaque in the public domain, accessible for use by citizen groups, providers or policy makers can be defined as transparency initiatives. Initiatives for transparency can be pro-active or reactive disclosure by government."
Kim et al. (2005) 
Data and information are available in a public, timely, free and easily interpretable manner.
‘Openness of the governance system through clear processes and procedures and easy access to public information for citizens [stimulating] ethical awareness in public service through information sharing, which ultimately ensures accountability for the performance of the individuals and organizations handling resources or holding public office.’
Varying concepts: Government transparency (Cato's Address Transparency in the Federal Bureaucracy); monetary transparency (Faust & Svensson, 1998's NBER paper); China (Brookings: Bernanke & Olson, 2016 & JP Horsley, 2018)
- Shin Y, Glennerster MR. Is transparency good for you, and can the IMF help?. International Monetary Fund; 2003 Jun 1.
- Note: Transparency discussed in terms of IOs and environmental policy | Bauhr, M., & Nasiritousi, N. (2012). Resisting transparency: Corruption, legitimacy, and the quality of global environmental policies. Global Environmental Politics, 12(4), 9-29. doi:http://dx.doi.org/10.1162/GLEP_a_00137
- Paunov, Y., WÄNKE, M., & Vogel, T. (2019). Transparency effects on policy compliance: Disclosing how defaults work can enhance their effectiveness. Behavioural Public Policy, 3(2), 187-208. doi:http://dx.doi.org/10.1017/bpp.2018.40
- Inventory of transparency policies globally | Michener G. Policy evaluation via composite indexes: Qualitative lessons from international transparency policy indexes. World Development. 2015 Oct 1;74:184-96.
- Child mental health policy | Gibson, J., Raphael, K., & Goodyer, I. (2015). A call for greater transparency in health policy development: Observations from an analysis of child and adolescent mental health policy. Evidence & Policy, 11(1), 7-18. doi:http://dx.doi.org/10.1332/174426414X13940168597987
- Vaccines} Author questions broadness of transparency | Dawson, A. (2009). Transparency, accountability and vaccination policy. Journal of Medical Ethics, 35(5), 274. doi:http://dx.doi.org/10.1136/jme.2009.029371
- Nigeria | Garuba HA, Kohler JC, Huisman AM. Transparency in Nigeria's public pharmaceutical sector: perceptions from policy makers. Globalization and health. 2009 Dec 1;5(1):14.
- European Medicines Agency transparency policy | [Risk-benefit relationship] "Conversely, policy makers are appropriately unwilling to tolerate health risks when the benefits are minimal or inadequately defined. Characterizing the risk-benefit relationship is critical to setting rational and appropriate public policy. Any discussion of the role of science in this endeavor is inadequately served without discussing these important relationships. | Kim, D. (2017). Transparency policies of the european medicines agency: Has the paradigm shifted? Medical Law Review, 25(3), 456-483. doi:http://dx.doi.org/10.1093/medlaw/fwx002
- US EPA } Armstrong, A. (2018, May 07). EPA seeks comment on scope of new science transparency policy. SNL Energy Coal Report Retrieved from http://utsph.idm.oclc.org/login?url=https://search.proquest.com/docview/2036325040?accountid=7134
- Schwartz, D. H. (2014). Policy and the transparency of values in science. Environmental Health Perspectives (Online), 122(11) doi:http://dx.doi.org/10.1289/ehp.1408936
*Interestingly and not surprisingly, transparency is discussed in monetary policy: "A useful definition of transparency and its potential benefits can be found in Swanson (p. 793):
• Transparency is the amount of information about the goals and conduct of monetary policy released to the public. Transparency should lead to an improvement in financial market and private sector understanding of how the central bank will set policy as a function of the state of the economy.
• This improved understanding should lead to an increase in the private sector’s ability to forecast the central bank’s policy instrument.
- Swanson, Eric T. 2006. “Have Increases in Federal Reserve Transparency Improved Private Sector Interest Rate Forecasts?” Journal of Money, Credit, and Banking, April. vol. 38, no. 3, pp. 791-819.
- Sellon G. Monetary policy transparency and private sector forecasts: evidence from survey data. Economic Review. 2008 Jun 22(Q III):7-34
 Code of Good Practices on Transparency in Monetary and Financial Policies, Part 1— Introduction, Approved by the IMF Executive Board on July 24, 2000. https://www.imf.org/external/np/mae/mft/code/index.htm
World Health Organization Outbreak Communication Planning Guide https://apps.who.int/iris/bitstream/handle/10665/44014/9789241597449_eng.pdf
 Kim et al. (2005). ‘Towards Participatory and Transparent Governance: Report on the Sixth Global Forum on Reinventing Government’, Public Administration Review 65.6: 646–654.