New findings from world’s largest study on children with Long-Covid

Recently published in Nature Communications Medicine, the Children and young people with Long-Covid (CLoCK) study is the world’s largest longitudinal cohort study on long-Covid in children.

The researchers, led by Professor Sir Terence Stephenson and Professor Roz Shafran, asked young people aged between 11 to 17 about their health three, six, 12 and 24 months after taking a PCR test for the Covid virus between September 2020 and March 2021. They also asked them to report their symptoms at the time of taking the test.

Most young people who were confirmed to have Long-COVID three months after a positive PCR test had recovered within 24 months.

In February 2022, the team published a consensus definition of Long-Covid which involved a young person having more than one symptom, such as tiredness, trouble sleeping, shortness of breath or headaches, alongside problems with either mobility, self-care, doing usual activities, having pain/discomfort, or feeling very worried or sad.

The researchers used this definition for their new study, which examined data from 12,632 young people who had a PCR test for Covid-19.

Of the 12,632 young people, there were 943 who had tested positive when first approached and who provided answers at every time point after their original test.

They found:

• At three months after their initial positive test, 233 young people had Long-Covid
• At six months, 135 continued to have Long-Covid
• At 12 months, 94 continued to have Long-Covid
• At 24 months, only 68 young people (7.2%) continued to have Long-Covid

Therefore, while 68 of the 233 (30%) still had Long-Covid 24 months after their confirmed Covid-19 infection, over two-thirds (70%) of the participants with symptoms at 3 months had recovered.

Researchers found that older teenagers and those from a more disadvantaged background were less likely to have recovered. Also, females were almost twice as likely to still meet the research definition of long-Covid at 24 months, compared to males.

However, some symptoms such as headaches and tiredness may be attributable to pre-menstrual syndrome given the high proportion of girls, and this wasn’t assessed in the research.

Study Chief Investigator and first author, Professor Sir Terence Stephenson, said: “Our findings show that for teenagers who fulfilled our research definition of long Covid three months after a positive test for the Covid virus, the majority have recovered after two years. This is good news but we intend to do further research to try to better understand why 68 teenagers had not recovered.”

The researchers also note that the original PCR tests were taken before the Delta and Omicron variants became dominant, so the findings may not reflect the long-term effects of these variants.

The CLoCK study is funded by the National Institute for Health and Care Research (NIHR) and UK Research and Innovation (UKRI).

The study was co-led by the UK Health Security Agency (UKHSA) in collaboration with researchers at Imperial College London, King’s College London, Manchester University NHS Foundation Trust, the Universities of Bristol, Cambridge, Edinburgh, Liverpool, Manchester and Oxford, and University College London Hospitals NHS Foundation Trust.