Children as young as five are having panic attacks about meeting friends for playdates, the NHS has said.
In January, the Centre for Mental Health (CMH) confirmed more than 500,000 previously healthy children had been pushed over the edge by the pandemic needing mental health support for the first time.
Now, NHS waiting lists of up to four years have forced more families to look for help from private psychologists only to find they are oversubscribed, according to a Telegraph investigation.
Leading private therapists have said they are taking twice the usual call numbers from concerned parents and have had to turn away patients or impose waiting lists for the first time.
New calculations seen by The Telegraph show that an extra 1.5million children and young people will need mental health support in the next three to five years “as a direct impact of the pandemic”.
The research, from the CMH, suggests demand will be up to three times the capacity of mental health services.
NHS England director for mental health Claire Murdoch said: “The pandemic has turned young people’s lives upside down.”
On Tuesday, the NHS will promise an additional £40m for children’s mental health services.
It comes after figures earlier in June revealed the number of people in England waiting to start NHS hospital treatment rose above five million for the first time.
Downing Street estimates showed the cost of fixing such waiting times could reach £40bn.
In its latest weekly surveillance report, Public Health England (PHE) said that the rate for 10 to 19-year-olds stood at 72.3 cases per 100,000 people in the seven days to May 30. This was up week-on-week from 55.1.
However, UK vaccine experts are unlikely to recommend coronavirus jabs for 12 to 17-year-old children imminently, the BBC has been told.