A randomized controlled trial to test the effect of simplified guidance with visuals on comprehension of COVID-19 guidelines and intention to stay home if symptomatic

BACKGROUND: In the COVID-19 pandemic, it is imperative that people understand and comply with self-isolation guidelines. We tested whether a simplified version of the guidelines and a simplified version with visual aids would affect comprehension and intention to self-isolate during the containment phase of the pandemic in the UK, in March 2020, compared to the standard guidelines. METHODS: We conducted an online, three-armed parallel randomized controlled trial. Participants were English and over 18. The survey software randomized them into conditions; they were blind to condition. The control group read the 7-page standard guidelines (the current version at the time of the trial). The intervention groups were given either a 3-page simplified version, with a summary box on the front page and numbered bullet points, or the same simplified version with pictograms illustrating the points in the box. Primary outcomes were comprehension of the guidelines, as measured by the number of correct answers given to six questions about the content, and the proportion who answered that they would ‘definitely’ stay at home for 7 days if symptomatic. FINDINGS: Recruitment was from 13 to 16 March 2020, with 1845 participants randomised and all data analysed. The Control group averaged 4.27 correct answers, the Simplified 4.20, and the Simplified + visual aids 4.13, out of a possible total of 6 correct answers. There were no differences in comprehension in the unadjusted models; however, when the model was adjusted for demographic variables, there was lower comprehension in the simplified + visual aids condition than in the control, (ß = − 0.16, p = 0.04998). There were no statistically significant differences in intention to stay home: Control was 85%, Simplified 83%, and Simplified + visual aids condition 84%. CONCLUSION: Simplified guidance did not improve comprehension compared to the standard guidance issued in the containment phase of the COVID-19 pandemic in March 2020, and simplified guidance with visual aids may even have worsened comprehension. Simplified guidance had no effect on intention to stay home if symptomatic. This trial informed COVID-19 policy and provides insights relevant to guidance production in the acute phase of a major public health emergency. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12889-021-10787-9.