Research from the Covid-19 Schools Infection Survey also showed most secondary school headteachers and pupils thought face coverings should be mandatory in schools.
The requirement to wear a mask in secondary school classrooms was removed on January 20 and the need to wear them in communal areas was dropped on January 27.
But data from surveys taken in January and February show 55 per cent of pupils said they “always” wore a mask inside school - but not in lessons - after the rules were changed. 50 per cent said they continued to wear one in lessons.
This is a drop from 68 per cent and 80 per cent respectively compared to before the rules changed.
Professor Punam Mangtani, co-chief investigator of the study at the London School of Hygiene & Tropical Medicine, said: “Parents and older pupils were clearly aware of the protection and benefit of wearing a mask when there was a new wave of high infection rates with a new variant, with a high percentage of secondary pupils and parents reporting that face masks help keep others and themselves safer.
“This is extremely promising and suggests that, should the need arise, the reintroduction of mask wearing could be understood and sustainable.”
Mask wearing in schools has been controversial, with some teaching unions calling the removal of the recommendation to wear them premature, but some parents running a ‘no masks in class’ campaign.
Tuesday’s data reveals most secondary school headteachers thought that face coverings should be mandatory in their schools while primary school headteachers did not.
A total of 61 per cent of secondary school headteachers said wearing masks in school “definitely” or “probably” should be made mandatory.
But 97 per cent of primary school headteachers said face coverings definitely or probably should not be made mandatory.
The parents of primary school pupils were more likely to say their children struggled with remote learning during the pandemic.
Some 42 per cent of parents of primary pupils said their child found it “difficult” or “very difficult”, compared with 38 per cent of parents of secondary school pupils.
The main problem identified by all parents, and pupils themselves, was “struggling with motivation.”
Dr Shamez Ladhani, Consultant Paediatrician at the UK Health Security Agency and the study’s chief investigator, said: “These findings show the impact of the pandemic on children, young people and their parents, and the difficulties of remote learning.
“Keeping students in school, where they feel more motivated and where more support is available, remains vital to their health, wellbeing and future prosperity.”
He added schools are also important for children’s health and wellbeing and for helping deliver routine childhood immunisations such as flu and the three-in-one booster for tetanus, diphtheria and polio.
He said: “Many children and young people may have missed out on their vaccinations because of the pandemic. Parents are encouraged contact their GP to get their child vaccinated where eligible, to protect themselves and those around them.”