Shevlin et al. (2021) recently demonstrated heterogeneity in mental health responses to the coronavirus disease 2019 (COVID-19) pandemic over time from a nationally representative sample of UK adults (March–July 2020). Five subpopulations representing either stability, deterioration or improvement in both anxiety-depression and COVID-19 posttraumatic stress disorder (PTSD) were identified. The majority of the sample were characterised by low levels of anxiety-depression (56.6%) and COVID-19 traumatic stress (68.3%) during this early phase of the pandemic but some showed deterioration and some showed mental health benefits. Here, we extend these findings using two additional survey waves from the COVID-19 Psychological Research Consortium (C19PRC) study, thereby modelling mental health trajectories for the UK population within the entire first year of the pandemic.