​FOI REF: FOI/2023/4847

You asked

The Scottish government claims that ONS data shows 187,000 reports of 'long COVID' are from within Scotland. Please see the following statement on Twitter: Scottish Parliament on Twitter

  1. Can you tell me how self-reported 'long COVID' estimates are generated by ONS?

  2. Is it possible reports of 'long COVID' could be other illnesses yet to be diagnosed?

  3. Is 'long COVID' a recognised medical diagnosis in the UK?

We said

Thank you for your enquiry.

Our estimates of the prevalence of self-reported long COVID are derived from responses to our Coronavirus (COVID-19) Infection Survey (CIS). Estimates are produced for four-week reference periods, whereby responses collected during each period are weighted to represent people aged 2 years and over living in private households in the UK. The survey questions relating to self-reported long COVID can be found in Section F of the enrolment and Section D of the follow-up CIS questionnaire. It is important to note that long COVID is an emerging phenomenon that is not yet fully understood. Therefore, our prevalence estimates are Experimental Statistics. The estimates are currently under development, which means that they may change as scientific understanding of long COVID improves. We advise caution when using the data.

Within the CIS, long COVID status is self-reported by study participants and so misclassification is possible. For example, some participants may be experiencing symptoms because of a health condition unrelated to COVID-19 infection. Others who do have symptoms caused by COVID-19 may not describe themselves as experiencing long COVID (for example, because of lack of awareness of the term or not knowing they were initially infected with COVID-19).

The clinical guideline on managing the long-term effects of COVID-19, developed by the National Institute for Health and Care Excellence (NICE), the Scottish Intercollegiate Guidelines Network (SIGN) and the Royal College of General Practitioners (RCGP), states that "the term 'long COVID' is commonly used to describe signs and symptoms that continue or develop after acute COVID‑19. It includes both ongoing symptomatic COVID‑19 (from 4 to 12 weeks) and post‑COVID‑19 syndrome (12 weeks or more)." Case definitions of ongoing symptomatic COVID‑19 and post‑COVID‑19 syndrome can be found within the guideline.

If you would like to discuss your enquiry further, please contact health.data@ons.gov.uk.