Women and younger adults were more likely to feel depressed during the second UK coronavirus peak than men and other age groups, Office for National Statistics (ONS) data suggests.
Four in 10 women aged between 16 and 29 were affected, compared to 26% of men.
One in five adults experienced depression in early 2021 – more than double pre-pandemic levels.
But GPs in England diagnosed fewer cases of depression in adults in 2020 compared with the year before.
Many people may not be seeking medical help, the ONS says.
However, the GP data – from March to August 2020 – may not include people who went to their GP last summer and were diagnosed with depression at a later point.
Before the pandemic began, 10% of adults said they experienced some form of depression.
Last autumn, following the first peak, ONS data suggested twice as many adults in Britain (19%) had feelings of depression as normal – and this new data suggests even more people were affected in early 2021 (21%).
Between January and March 2021, disabled people, adults who are extremely vulnerable and those living in the most deprived areas of England were more likely to say they felt depressed than other groups.
And rates of depressive symptoms more than doubled in adults aged 16 to 39 years old, to 29%.
The ONS analysis was based on 25,935 adults answering a questionnaire which asked about their feelings. One of the eight questions posed was: “Over the last two weeks, how often have you been bothered by having little interest or pleasure in doing things?”
A score of 10 or more indicated moderate to severe depression symptoms.