: Clear communication of scientific evidence remains important, as dramatically highlighted by COVID-19. But what does clear communication look like if the evidence keeps changing? Along with the known problems of fake news, disengagement and science scepticism, there is the problem of scientists presenting conflicting views on the same topic. Alternatively, changing evidence can lead to scientists saying something but, in the light of new evidence, revising their conclusions and the scientific message. In the case of COVID-19, the lack of clear scientific messaging in the early days of the pandemic opened the debate to politics and culture, lowering trust in science and politicizing mitigation measures such as mask wearing. What lessons can be learned from the COVID-19 experience in order to improve future scientific communication, even in the face of uncertain evidence? What are the roles of different actors, such as epidemiologists, behaviour change specialists, science journalists, policymakers and international actors like the WHO in shaping this narrative? How can they improve their future collaboration so that scientific communication with the public becomes more transparent, equitable and trust-building? Short presentations: Prophylactic measures taken in times of COVID-19 - Ricardo Mexia, Portugal (vice-president EUPHA-IDC). Contribute to the effectiveness of COVID-19 prevention measures, by making available state-of-the-art behavioural and communication science expertise - Mariken Leurs, RIVM. Key considerations for risk communication and community engagement - Cristiana Salvi, Communication Officer, WHO Europe. How protective masks went from don't wear to must have - Megan Molteni, journalist. Panel discussion with the audience. KEY MESSAGES: Transparency in communicating evidence is essential for clear and usable communication. Open dialogue on what we know and what we do not yet know is key to communication evidence.
4.F. Round table: Clear communication in the face of changing evidence: the example of COVID-19 prophylaxis