UK statistics tsar rebukes Health Security Agency over flawed jabs data

The head of the UK statistics regulator has chastised England’s public health body for publishing “misleading” Covid-19 vaccination data that has been used by anti-vaxxers to cast doubt on the effectiveness of jabs.

The UK Health Security Agency had “slipped up” by releasing data in its weekly vaccine surveillance report that showed infection rates among fully vaccinated people aged 40 and above were higher than among their unvaccinated counterparts, Sir David Norgrove, chair of the UK Statistics Authority, said on Thursday evening.

“Those numbers were misleading and wrong and we’ve made it very clear to UKHSA,” Norgrove said at an event organised by University College London. “I’m lost for words at the willingness to publish a table that led people to believe that, with a footnote that was too weak.”

The UKHSA report has become a favoured piece of evidence for anti-vaxxers and vaccine sceptics online, since it first featured the contentious data in early September.

In the UK, the lockdown-sceptic Hart group of scientists, academics and medics has referenced the report. The findings were also pored over by vaccine sceptic Alex Berenson in a segment on US comedian Joe Rogan’s podcast on Spotify, whose episodes draw audiences of an estimated 11m people.

“This is UK government data and what it says is that the idea that this is a pandemic of the unvaccinated is a total lie,” said Berenson, who was banned from Twitter in August for spreading Covid-related misinformation. “You are more likely to become sick if you are vaccinated than if you are not, and . . . above 40.”

The skewed data stem from the use of the National Immunisation Management Service (Nims) records used by the health agency in its calculations. Nims relies on lists of patients registered with family doctors and is therefore susceptible to double-counting because of people failing to deregister with their GP when they move home, according to Norgrove.

The “error” occurs because GP data overestimate the number of unvaccinated people, masking the real rate of Covid-19 infection in that group, added Norgrove.

On Thursday, the UKHSA added two pages of caveats to their report, stressing there were “underlying statistical biases” in the infection rates’ comparison, including, for instance, the greater willingness of fully vaccinated people to get tested, which gives rise to a higher number of positive test results for this group.

But the data table remains in the report, with a new label to recognise the rates are “unadjusted” to offset discrepancies between the two groups.

Dr Mary Ramsay, UKHSA head of immunisation, accepted there had been “some misunderstanding and, at times, deliberate manipulation of the data presented” in the report. “To make the data less open to deliberate misinterpretation, we have changed the way it is presented to ensure clarity.”

But David Spiegelhalter, chair of the Winton Centre for Risk and Evidence Communication at Cambridge university, a statistical research institute, said the “minor changes” failed to address the problem.

“These effects will be minor compared to the gross distortions produced by using incorrect population figures,” said Spiegelhalter, adding “some footnote warnings cannot compensate for calculating such hopelessly biased rates”.

Spiegelhalter called on the UKHSA to feature the controversial data alongside alternative figures from the Office for National Statistics that “reduce this bias” and that the health agency already uses on its Covid data dashboard.

Norgrove said he had not seen the latest amendments to the report, but added that if it “continues to be misleading . . . we won’t let it rest”. Last year, the UK statistics tsar reprimanded former health secretary Matt Hancock for exaggerating coronavirus testing figures in June.

Stian Westlake, chief executive of the Royal Statistical Society, called on UKHSA to “turn the volume up to 11 on the corrections”.

“It does feel like quite a bit of damage has been done by this stat being out there, as anti-vaxxers have repeatedly used it to bolster their case,” said Westlake.

“Official stats are not always going to be perfect, but this is an example of why it’s so important to get things right from the start.”