Hundreds of thousands of Covid-19 cases still being missed from official figures

High levels of under-reporting are exposing the limitations of the daily case numbers.

11 February 2022

Hundreds of thousands of Covid-19 cases are continuing to be missed from the official figures each week, despite the recent decision to start including reinfections, new analysis shows.

An average of 101,000 cases of coronavirus per day were recorded from January 16 to 22, according to the Government’s Covid-19 dashboard.

But the true number was likely to be nearer 280,500 a day, according to estimates by the Office for National Statistics (ONS).

It means more than 1.2 million cases will not have been included in the official count during the week to January 22.

HEALTH Coronavirus Statistics
(PA Graphics)

The sharp difference in totals reflects the increasing limitations of the Government figures, which count only those people who have reported themselves as having tested positive for the virus.

The numbers are affected by how many people are coming forward for tests, have chosen to report their test results, or who are taking a test because they know they have coronavirus symptoms.

By contrast, the ONS figures are based on analysis of nose and throat swabs taken from a representative sample of more than 150,000 people in private households.

The same people are sampled every week, regardless of whether they know they have Covid-19 or have reported a positive result.

The ONS then produces estimates of the likely number of cases of coronavirus across the country.

The ONS figures, which are published as part of the weekly infection survey, are the most reliable snapshot of both the prevalence and volume of coronavirus across the country.

Between a half and two-thirds of all cases are likely to have been missed from the official figures in recent weeks, according to analysis by the PA news agency.

An average of 358,500 people were being infected with Covid-19 each day in the UK in the first week of January, around twice the equivalent number on the Government dashboard.

The latest figures, for the week to January 22, show the gap has grown even larger, with the ONS estimate of 280,500 cases a day nearly three times the dashboard average of 101,000.

At the peak of the recent Omicron wave of the virus, over Christmas and the new year, nearly half a million people in the UK are likely to have been infected with Covid-19 every day – far higher than the 189,800 a day in the Government figures.

Although the dashboard numbers were recently revised to include reinfections in England and Northern Ireland, this has not narrowed the gap with the ONS estimates.

The recent change in the rules for testing, removing the the need for asymptomatic people to have a confirmatory PCR test after a positive lateral flow result, will have affected the Government figures still further.

Scrapping the requirement for a follow-up test “has influenced testing behaviours” with “many more individuals” no longer taking a PCR test and therefore not likely to be included in the dashboard numbers, according to Public Health Wales.

Professor Kevin McConway of the Open University said there are “many reasons” why an infection might not end up being counted on the dashboard.

“Probably the most important is that people who are infected but have no symptoms may not be tested, and if you aren’t tested you can’t be a confirmed case,” he said.

“Even allowing for the margin of error in the ONS survey results, it’s very clear that the confirmed case count misses a large proportion of new infections.”

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