The investigation, which obtained data from half of England’s Child and Adolescent Mental Health Services (CAMHS), found that 49 per cent of young people waited more than four weeks to be seen between April 2020 and March 2021.
Of those who received specialist care in the past year, 51 per cent were seen in under four weeks.
The average wait was more than two months, Freedom of Information requests found.
CAMHS is a network of NHS psychologists, psychiatrists, nurses and social workers who support children with mental health difficulties.
Dr Catherine Hayhurst from the Royal College of Emergency Medicine told the BBC that some young people had been admitted to general wards in hospitals because they had nowhere else to go.
“Children are distressed and agitated. It’s difficult to manage on the wards,” she said.
Emma Thomas, chief executive of mental health charity YoungMinds, described the waits as “agonising” for young people.
She said the charity has seen a “big rise” in referrals to mental health services, which are struggling to cope.
“The pandemic has had a huge impact on young people’s mental health, exacerbating existing pressures and creating new ones,” she said.
“The young people we work with have told us that they have struggled with isolation, loneliness and concerns about the future, whilst those that experienced trauma during the lockdowns, or were already experiencing inequalities, are likely to be disproportionately affected,” she added.
In June, the NHS announced that CAMHS will receive an additional £40m in funding to address the impact of the Covid-19 pandemic on children’s mental health.
The funding will be used to provide additional training to staff, as well as improve support services to prevent the need for hospital admission.
Claire Murdoch, the national mental health director, said she hopes the funding will help young people receive “the best care as early as possible”.
“This pandemic has hit our young people hard and while services have remained open throughout, we have seen an increase in the numbers of children and young people seeking help from the NHS for their mental health.
“This additional funding is in recognition of the rising demand and our continued commitment to provide the best care as early as possible,” she said.