This dataset represents the anonymised data collected as part of the Viral Communication (Understand-ELSED) project. It includes the two measurements, Phase I (30 October 2020 and 14 December 2020) and Phase II (2 March 2021 and 22 March 2021). As the dataset involves two measurements (i.e., Phase I and Phase II), it is split into two sections, each of which can be identified by looking at the variable names. Variables corresponding to the Phase I survey will have the prefix “PHASE1_”, while variables from the Phase II survey will have the prefix “PHASE2_”. Exceptions to this are the socio-demographic variables from the main section of the Phase I survey. Each questionnaire was split into a main and an opt-in section, the cut-off points of which are located after the variables PHASE1_OI_AQ and PHASE2_OI_AQ, respectively. Furthermore, two sets of two weighting variables were calculated. The first set includes weights for analyses only involving Phase I variables, while the second set contains weights for analyses involving any Phase II variables. The corresponding variable labels specify how to use any of the weighting variables, which are located in positions 2 through 5. In the Phase II survey, we included two experimental setups. For the vaccination origin experiment, we included a grouping variable, PHASE2_HM_VACC_GROUP. The same was done for the risk assessment experiment, with PHASE2_RA_INF_GROUP being the grouping variable.