The beginning of 2020 will forever be remembered as the era of COVID-19’s global spread. People all over the world experienced quarantines, behavioral restrictions and were asked to take a variety of measures in order to reduce the risk of contracting COVID-19. However, many official recommendations, their importance and their enforcement were ambiguous and open to interpretations. Therefore, in many cases people relied on their own risk assessments when considered whether and how to conform to social distancing and related recommendations. Previous literature had demonstrated that in many cases, risk assessments are prawn to be biased. In this study, we examined the impact of presenting events conjunctively or disjunctively on risk assessments and whether biased assessments are correlated with prevention and protection behavior. Results show that people tend to overestimate the likelihood of contracting Covid-19 when events are conjunctive rather than disjunctive. In addition, we found that people who demonstrated negative attitude toward vaccination, had greater tendency for biased risk assessments.