Transparency: A central principle underpinning trustworthy guidelines

• The development of trustworthy guidelines follows a range of principles. • In response to the Covid pandemic there was an urgent need for guidelines to respond to a wide range of clinical and public health challenges; timelines became contracted and evidence was frequently lacking or of poor quality. • For guideline development the World Health Organization, it became clear that one of the most important principles to adhere to is transparency as this underpins all other principles of guideline development.