Long Covid in Children: ONS Prevalence estimates have been radically revised downwards
We read with interest Majeed and colleagues’ examination of specific consent-issues regarding Covid-19 vaccines in children given what they describe as a “finely balanced risk-benefit profile” for vaccination . In our previous letter (“Vaccinating children to prevent long covid? More caution is needed in interpreting current epidemiological data”), published in February 2021 we warned that Office for National Statistics (ONS) data on post Covid-19 symptoms were not at that time fit for the purpose of informing medical- and public-health decisions in children because symptoms often ascribed to this condition are very common and non-specific, and because of a lack of a comparator group of non-infected children for proper comparison of prevalence estimates. The figures quoted at that time (12.9% or primary-school aged, and 15% of secondary-school aged children displaying one of twelve symptoms at five-weeks post-infection) were being frequently discussed including in the mainstream media. The fact-checking website FullFact ran a piece encouraging more thoughtful discussion in March 2021. Nonetheless, we continued to observe these data being used uncritically and think it is possible that these ideas remain in the mind of the public, although we see that official consent-materials for children state “For most children and young people COVID-19 is usually a milder illness that rarely leads to complications. For a very few the symptoms may last for longer than the usual 2 to 3 weeks.”.
We therefore were pleased to note further ONS data-releases on the subject. In April 2021, similar estimates were revised downwards considerably to 7.4% (primary-school aged) and 8.2% (secondary school aged children). In September 2021 these were further revised downwards to 3.3% (95%CI 2.5-4.5) in primary-school aged children and 4.6% (95%CI 3.5-6.0) in those of secondary-school age for children at 4-8 weeks post-infection. Crucially, in these latest figures a matched-control group of children had similar prevalence of ‘long covid’ despite being likely to have never had Covid-19 disease (3.6% [95%CI 2.7-4.8] and 2.9% [95%CI 2.1-4.0] for primary- and secondary-school aged children respectively)  . Reduced prevalence estimates and similarity with controls are also seen in equivalent figures for those with continuous symptoms, and for those with who self-reported positively in response to the question “Would you describe yourself as having ‘long COVID’, that is, you are still experiencing symptoms more than 4 weeks after you first had COVID-19, that are not explained by something else?”.
It is clear to us that early concerns over high prevalence of post-covid syndromes were exaggerated. This may have been due to outcome-misclassification bias in the ONS data (see Figure 3 ), issues with long-term follow up for symptoms beyond 12-weeks post-infection, lack of a test-negative comparator-group in early ONS data releases and in other studies, and lack of a child-specific definition for post-covid syndrome given that we know ‘children are not small adults’ (this is under development ). Whatever the reasons, in our view, public discussions on ‘Long Covid’ and children have not always helped children, their parents and caregivers. We continue to encourage both a more cautious approach in applying adult-focussed epidemiological methods to children, and support for all children who need it throughout and beyond the remaining pandemic period.
1 Majeed A, Hodes S, Marks S. Consent for covid-19 vaccination in children. BMJ 2021;374:n2356. doi:10.1136/bmj.n2356
2 Bhopal SS, Absoud M. Vaccinating children to prevent long covid? More caution is needed in interpreting current epidemiological data. BMJ 2021;372:n520. doi:10.1136/bmj.n520
3 Updated estimates of the prevalence of long COVID symptoms - Office for National Statistics. https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/... (accessed 3 Feb 2021).
4 Extrapolating figures around long Covid in kids is not the way to go. Full Fact. https://fullfact.org/health/extrapolating-figures-around-long-covid-kids... (accessed 25 Mar 2021).
5 COVID-19 vaccination: a guide for eligible children and young people aged 12 to 17. GOV.UK. https://www.gov.uk/government/publications/covid-19-vaccination-resource... (accessed 4 Oct 2021).
6 Prevalence of ongoing symptoms following coronavirus (COVID-19) infection in the UK - Office for National Statistics. https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/... (accessed 4 Oct 2021).
7 Office for National Statistics. Technical article: Updated estimates of the prevalence of post-acute symptoms among people with coronavirus (COVID-19) in the UK: 26 April 2020 to 1 August 2021. https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/...
8 Public Health England & UCL. Children and young people with Long Covid (CLoCK). https://assets.publishing.service.gov.uk/government/uploads/system/uploa...
Competing interests: No competing interests