Estimating Long COVID

What is the prevalence of this post-COVID syndrome?

Anthony B. Masters


Prof Anthony Costello (UCL) gave evidence to an all-parliamentary group of MPs. The social media account for this all-parliamentary group summarised his contribution:

The worry is this — we do not really understand Long Covid and what it means. We don’t know how long this lasts in people’s bodies. There is a lot to be concerned about.

There are 19 million children in the UK. If we just let them remain un-vaccinated, half of them become infected. That is 9.5 million[.] If 15% or 13% get prolonged symptoms, that could mean 1.3–1.5 million children.

This article looks at estimations of Long COVID, and the claim about the number of children in the UK.

What is ‘Long COVID’?

Some people who contract COVID-19 may experience symptoms for a long time. The National Health Service website states:

Emerging evidence and patient testimony is showing a growing number of people who contract COVID-19 cannot shake off the effects of the virus months after initially falling ill.

In some patients, the virus casts a long shadow. (Image: Lockton Interational)

The Office for National Statistics conducts an infection survey, testing for SARS-CoV-2. This is the virus that causes COVID-19.

After five weeks, the estimated share of young people reporting symptoms is:

  • Age 2–11 years: 12.9% (10.4% — 16.0%)
  • Age 12–16 years: 14.5% (11.7% — 17.9%)

This survey appears to the source for the “15% or 13%” figures. For all people, the symptomatic share after five weeks was 22% (21% — 23%).

The symptoms include fatigue, coughs, headaches, fever, loss of taste, and loss of smell. There is also myalgia, sore throat, breath shortness, nausea, diarrhoea, and abdominal pain. The survey estimate is between 22nd April and 14th December 2020.

5 and 12 weeks

The ONS compared post-infection symptoms at two different cut-offs:

  • Symptomatic at 5 weeks: 21.0% (19.9% — 22.1%)
  • Symptomatic at 12 weeks: 9.9% (6.7% — 14.7%)



Anthony B. Masters

This blog looks at the use of statistics in Britain and beyond. It is written by RSS Statistical Ambassador and Chartered Statistician @anthonybmasters.