Hundreds of thousands of Covid-19 cases continue to be missing from official figures every week, despite the recent decision to start including reinfections, analysis shows.
An average of 101,000 daily coronavirus cases were recorded from January 16 to 22, according to the government’s Covid-19 dashboard.
But the true number was probably closer to 280,500 a day, according to Office for National Statistics (ONS) estimates for the same period. This means more than 1.2 million cases will have been missed from the official tally in the week to January 22.
The stark difference in the totals reflects the growing limitations of government figures, which only count people who have reported themselves as having tested positive for the virus.
The numbers are affected by how many people are coming in for tests, choosing to report their test results, or taking a test because they know they have symptoms of coronavirus.
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, whether they know they have Covid-19 or have reported a positive result. The ONS then produces estimates of the likely number of coronavirus cases across the country.
The ONS figures, which are released as part of the weekly Infections Survey, are considered the most reliable snapshot of the prevalence and volume of coronavirus across the country.
There were 58,899 cases of Covid-19 reported in the UK on Friday, the government said, and a further 193 people died within 28 days of testing positive for Covid-19, bringing the total to 159,158.
At the height of Omicron’s recent wave of the virus, over Christmas and New Year, nearly half a million people in the UK are likely to have been infected with Covid-19 each day – far more than the 189 800 a day to government Figures. Although the dashboard figures were recently revised to include reinfections in England and Northern Ireland, this did not close the gap with the ONS estimates.
The recent change in testing rules, removing the need for asymptomatic people to undergo a confirmatory PCR test after a positive lateral flow result, will have further affected government figures.
Public Health Wales said the removal of the requirement for a follow-up test ‘has influenced testing behaviours’ with ‘many more people’ no longer taking a PCR test and therefore unlikely to be included in the figures of the dashboard.
Open University professor Kevin McConway said there were “many reasons” why an infection might not be counted on the scorecard.
“The most important thing is probably that people who are infected but don’t show any symptoms don’t get tested, and if you don’t get tested you can’t be a confirmed case,” he said. “Even allowing for the margin of error in the results of the ONS survey, it is very clear that the number of confirmed cases misses a large proportion of new infections.