One in four middle-aged adults who test positive for Covid no longer follow the rules on self-isolating, the latest polling suggests.

Some 75 per cent of respondents aged between 35 and 54 said they adhered to isolation requirements for the entire 10-day period after testing positive for the virus. This was down from 86 per cent in the summer, according to the Office for National Statistics (ONS).

The statistics – based on a  survey of 881 people in England in late September and early October – suggests those in their mid-30s to mid-50s are the least likely of all age groups to follow the requirements of self-isolation in full.

Compliance also fell in older people, with adherence dropping marginally in those aged 55 and over from 81 per cent in the summer to 78 per cent in recent weeks, according to the ONS.

However, young people are now more likely to follow the rules than was the case in the summer, with 82 per cent of 18 to 34-year-olds reporting full compliance, up from 75 per cent in the summer.

The figures are based on responses collected in England between Sep 27 and Oct 2. They suggest most people are still following the requirement to self-isolate, with adherence among all adults standing at 78 per cent.

This is broadly unchanged from 79 per cent in the previous survey in July but is “significantly lower” than levels seen earlier in the year, such as 86 per cent in May, the ONS said.

The proportion of people saying self-isolation has affected their well-being has fallen. The survey found that 34 per cent of those who tested positive for Covid reported that isolating had a negative effect on their mental health, down from 42 per cent in July.

The ONS added that the figures should be treated with care because the survey was based on a relatively small sample of respondents who chose to report their own behaviour.