This research explored experiences across three cognitive function groups (no impairment, mild impairment, and dementia) with respect to shielding (either self-isolating or staying at home), COVID-19 infection, and access to health/care services during the COVID-19 pandemic. Analyses were conducted using data from the English Longitudinal Study of Ageing (ELSA) COVID-19 sub-study collected in 2020. We report bivariate estimates across our outcomes of interest by cognitive function group along with multivariate regression results adjusting for demographic, socioeconomic, geographic, and health characteristics. Rates of shielding were high across all cognitive function groups and three measured time points (April, June/July, and Nov/Dec 2020), ranging from 74.6% (95% confidence interval 72.9-76.2) for no impairment in Nov/Dec to 96.7% (92.0-98.7) for dementia in April (bivariate analysis). 44.1% (33.5-55.3) of those with dementia experienced disruption in access to community health services by June/July compared to 34.9% (33.2-36.7) for no impairment. A higher proportion of those with mild impairment reported hospital-based cancellations in June/July (23.1% (20.1-26.4)) and Nov/Dec (16.3% (13.4-19.7)) than those with no impairment (18.0% (16.6-19.4) and 11.7% (10.6-12.9)). Multivariate adjusted models found that those with dementia were 2.4 (1.1-5.0) times more likely than those with no impairment to be shielding in June/July. All other multivariate analyses found no statistically significant differences between cognitive function groups. People with dementia were more likely than people with no impairment to be shielding early in the pandemic, but importantly they were no more likely to experience disruption to services or hospital treatment.