One in four young adults who test positive for Covid-19 no longer follow the rules for self-isolating, a new survey suggests.

Some 75% of respondents aged between 18 and 34 said they fully adhered to the isolation requirements for the entire 10-day period after testing positive for coronavirus.

This was “statistically significantly” lower than the percentage of 35 to 54-year-olds who said they followed the rules (86%), according to the Office for National Statistics (ONS) which compiled the survey.

The figures are based on responses collected from adults in England between July 5 and 10.

They suggest that most people are still following the requirement to self-isolate, though levels have dropped in the past two months.

Some 88% of 18 to 34-year-olds said they were adhering to self-isolation rules when surveyed between May 10 and 15, compared with 75% in the latest survey.

Adherence among all adults has fallen from 86% in May to 79% in July.

The proportion of people saying that self-isolation has affected their wellbeing has risen, however.

Around four in 10 (42%) of those who tested positive reported that isolating had had a negative effect on their mental health, up from 37% in May.

And 31% reported having lost income due to self-isolation, up from 27%.

Tim Gibbs, head of the ONS public service analysis team, said: “Full adherence to self-isolation requirements after testing positive for Covid-19 remains high, though we have seen a drop from May to July.

“Self-isolation can have a negative impact on wellbeing and finances – nearly one third of people reported they lost income as a result of adherence and four in 10 said self-isolation had a negative impact on their wellbeing and mental health.

“With restrictions having relaxed further, it is important we continue to monitor the behaviour of those required to self-isolate.”

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