The objectives of this study were to assess the trends in anxiety and depression levels in older adults nearly 10 months after the outbreak of coronavirus disease 2019 (COVID-19) and explore its determinants. A longitudinal study was performed between October 2019 and December 2020. The Patient Health Questionnaire 9-Item Scale and the Generalized Anxiety Disorder 7-Item Scale were used to assess depression and anxiety. Data were collected before (wave 1), during (wave 2), and 10 months after the COVID-19 outbreak (wave 3). The prevalence of depressive symptoms in the elderly was found to be 18.9%, 28.1%, and 35.9% at wave 1, wave 2, and wave 3 respectively. The prevalence of depressive symptoms at wave 1 was lower than that at wave 2 (χ2 = 15.544, P < 0.001) and wave 3 (χ2= 44.878, P < 0.001). There was no significant change in the prevalence of anxious symptoms (wave 1, 28.5%, wave 2, 30.3%, and wave 3, 30.3%). Older adults who were single/divorced/widowed had higher levels of anxiety compared with those who were married (OR = 2.306 95%CI 1.358–3.914, P = 0.002). The pandemic appeared to be associated with increases in depressive symptoms in older persons. Targeted interventions could be carried out among those with higher risk of maladjustment.