This study investigates the effects of several risk communication formats on the adequacy of people’s risk awareness/understanding in four different Western countries. Risk awareness/understanding is measured for both current risk and near futre risk. We also distinguish between the risk of meeting someone who has the coronavirus and the risk of getting infected with the coronavirus. Understanding of exponetial growth is also assessed. In particular, two risk communication formats are investigated: (1) an optimized format conveying individual risk (a numerical part to whole format with icon array that explains the absolute number of infectious people) versus the current standard format conveying only the absolute number of infectious people; (2) an optimized format conveying exponential growth (a numerical R-factor with icon array that explains the phenomenon of exponential growth) versus the current standard format conveying only the R-number and versus no exponential growth information at all. Furthermore, the study explores potential differences in effects among those with higher numeracy versus those with lower numeracy; among those with individualistic versus those with collectivistic values; and between respondents in the different countries. The study also explores the effects of the risk communication formats on several secondary outcomes, i.e. acceptance of behavioral measures, intention to get vaccinated, risk pereption and worry, relationships between risk awareness/understanding before and after exposure to the information and relationships between risk awareness/risk understanding and the seconadry outcomes.