Up to one in seven children who test positive for coronavirus could still have symptoms linked to the disease three months later, according to a study that suggests the prevalence of long Covid in young people is lower than initially feared.
The analysis, led by University College London and Public Health England researchers, drew on survey responses from nearly 7,000 11- to 17-year-olds who underwent PCR tests between January and March. Of these, 3,065 tested positive and 3,739 tested negative.
Many children in either group reported at least one symptom associated with coronavirus when surveyed at an average of 15 weeks after their test. Roughly 30% of those in the positive group reported having at least three or more symptoms after that time, and about 16% in the negative group.
The difference between the two groups suggests the symptoms of about one in seven children in the positive group could have been linked to Covid. The most common symptoms included unusual tiredness and headaches.
“The difference between the positive and negative groups is greater if we look at multiple symptoms, with those who had a positive test twice as likely to report three or more symptoms 15 weeks later,” said the study’s lead author, Sir Terence Stephenson, a professor at UCL Great Ormond Street Institute of Child Health and chair of the Health Research Authority.
When extrapolated to all those in the 11-17 age group who tested positive between September and March in England, the findings suggest that somewhere between 4,000 and 32,000 young people may have had three or more symptoms tied to Covid-19 infection after 15 weeks.
Reassuringly, the researchers found no differences in mental health and wellbeing scores between children who tested positive or negative. However, four in 10 participants – regardless of whether they tested positive or negative – said they were worried, sad or unhappy, which may reflect the general anxiety around the pandemic.
The prevalence figures are very much of the same order of magnitude as reported by the Office for National Statistics, which reflects estimates of self-reported long Covid prevalence of any duration. ONS figures indicate that about 31,000 people in the 11-17 age group have long Covid, said Stephenson. “That’s the kind of ballpark we’re in.”
However, these estimates are “definitely lower than the worst-case scenarios that were being portrayed last December,” he said.
Given the analysis was based on tests conducted up to March 2021, it is unclear how these findings may translate for the Delta variant, which only began dominating from May onwards. Data shows Delta is far more transmissible and capable of causing more serious disease than previous variants, particularly in adult unvaccinated populations.
Dr Deepti Gurdasani, a clinical epidemiologist at Queen Mary University of London, noted that at the peak of infections in children in July, about 14,000 children were being infected per day.
“One in seven would mean about 2,000 developing persistent symptoms for 15 weeks every single day. How on earth is this reassuring?” Gurdasani said.
The Joint Committee on Vaccination and Immunisation (JCVI) has recommended that children over 12 in the UK get vaccinated only if they are clinically extremely vulnerable or live with somebody at risk.
Dr Liz Whittaker, another of the study’s authors and a senior clinical lecturer in paediatric infectious diseases and immunology at Imperial College London, said: “Most of the young people that we’ve seen were symptomatic, but they’re very mildly symptomatic. Long Covid in young people isn’t something that follows severe disease. Vaccination prevents severe disease. So it’s very difficult to link those in a vaccination decision.”
The authors highlighted that this study, which is yet to be peer-reviewed, is particularly robust because it used the gold-standard PCR test for infection status instead of the less reliable self-reported status or lateral flow tests, and because it included a Covid-negative comparison control group.