The coronavirus pandemic continues to disrupt education in unprecedented ways. The first school closures in Ireland took place in March 2020, affecting many students, but especially those who were preparing for their end-of-school Leaving Certificate (LC) examinations. The aim of this study was to assess the extent to which COVID-19 had impacted the health and wellbeing of the 'class of 2020'. Some comparisons were also made with a 2015 health and wellbeing survey undertaken in Ireland. A total of 959 LC students completed an online survey. The findings demonstrated substantial negative impacts of COVID-19 on overall health and wellbeing. The comparison with the 'pre-COVID' (2015) sample of LC students also showed that the current cohort was faring statistically significantly worse across several domains. This is the only study to investigate the health and wellbeing of this cohort in the context of COVID-19. The findings provide important insights into impacts on student mental health and wellbeing; they also raise questions about how those who went on to Third Level, are faring, in light of continuing disruption to their studies and in the context of the already large numbers of Third Level students presenting with mental health problems in Ireland (and elsewhere).