Background Oral manifestations and lesions could adversely impact the quality of people’s lives. COVID-19 infection may interact with smoking and the impact on oral manifestations is yet to be discovered. Objectives The aim of this study was to assess the self-reported presence of oral lesions by COVID-19-infected young adults and the differences in the association between oral lesions and COVID-19 infection in smokers and non-smokers. Methods This cross-sectional multi-country study recruited 18-to-23-year-old adults. A validated questionnaire was used to collect data on COVID-19-infection status, smoking and the presence of oral lesions (dry mouth, change in taste, and others) using an online platform. Multi-level logistic regression was used to assess the associations between the oral lesions and COVID-19 infection; the modifying effect of smoking on the associations. Results Data was available from 5,342 respondents from 43 countries. Of these, 8.1% reported COVID-19-infection, 42.7% had oral manifestations and 12.3% were smokers. A significantly greater percentage of participants with COVID-19-infection reported dry mouth and change in taste than non-infected participants. Dry mouth (AOR=, 9=xxx) and changed taste (AOR=, 9=xxx) were associated with COVID-19- infection. The association between COVID-19-infection and dry mouth was stronger among smokers than non-smokers (AOR = 1.26 and 1.03, p = 0.09) while the association with change in taste was stronger among non-smokers (AOR = 1.22 and 1.13, p = 0.86). Conclusion Dry mouth and changed taste may be used as an indicator for COVID-19 infection in low COVID-19-testing environments. Smoking may modify the association between some oral lesions and COVID-19-infection.

UNSTRUCTURED Objectives: To assess the reported presence of oral lesions in COVID-19-infected young adults and the difference between smokers and non-smokers in this association. Methods: This cross-sectional multi-country study recruited 18-to-23 year-old adults using an electronic validated questionnaire assessing COVID-19-infection, smoking and the presence of oral lesions/conditions (dry mouth, change in taste, and others). Multi-level logistic regression assessed the association between oral lesions and COVID-19 infection, and how smoking modified the associations between COVID-19 and oral lesions/conditions. Results: Data was available from 5342 respondents from 43 countries. Of these, 8.1% reported COVID-19-infection, 42.7% had oral lesions and 12.3% were smokers. A significantly greater percentage of COVID-19-infected participants reported dry mouth and change in taste than non-infected persons. Smokers had significantly higher odds of stained teeth with COVID-19 infection than non-smokers (AOR: 1.24 and 1.00; p=0.02). The association between COVID-19-infection and dry mouth was stronger among smokers than non-smokers (AOR=1.26 and 1.03, p=0.09) while the association with change in taste was stronger among non-smokers (AOR=1.22 and 1.13, p= 0.86). Conclusion: Dry mouth and changed taste were associated with COVID-19-infection and may be used to screen for COVID-19 in low COVID-19-testing environments. Smoking may modify the association between some oral lesions and COVID-19-infection.