Coronavirus: Government’s Covid vaccine data ‘providing material for conspiracy theorists’
25 October, 2021
The UK government is “providing material for conspiracy theorists around the world” by publishing graphs on vaccine efficacy that it knows to be untrue, leading scientists have said.
Statisticians lambasted the Health and Security Agency for its weekly vaccine surveillance report, which erroneously suggests that vaccines make you more likely to contract Covid.
The findings are being used by anti-vaxxers to claim the vaccines are dangerous, but can largely be explained by a statistical anomaly in the calculation of population sizes.
David Spiegelhalter, director of the Winton Centre for Risk and Evidence Communication at Cambridge, said that continuing to publish in the way they are is highly damaging. “This presentation of statistics is deeply untrustworthy and completely unacceptable,” he said.
Across most age groups, the UKHSA report, which investigates vaccine efficacy, now shows case rates higher among the vaccinated than unvaccinated. For instance, among 50-59-year-olds it claims the Covid rate per 100,000 people is over 1,000 if you are vaccinated or half that if you are not.
This has been seized upon around the world. The numbers have been promoted by members of Hart, a UK group that publishes vaccine misinformation. They have also been quoted on the Joe Rogan Experience podcast in the US, which reaches 11 million people.
Appearing on that podcast, Alex Berenson, a US journalist now banned from Twitter, specifically referenced the source to show it was reliable.
“This is UK government data, and what it says is the idea that this is a pandemic of the unvaccinated is a total lie,” he said. “You are more likely to become sick if you are vaccinated than if you are not.”
It is difficult to calculate the true effects of vaccines from population data, because those who are vaccinated may behave very differently from those who are not. The main reason for the apparent discrepancy, though, is the population data itself — which overestimates the unvaxxed population.
The UKHSA estimates the population of each age group using data from the National Immunisation Management System. It then uses vaccination data to give the vaccinated population, and assumes the remainder is unvaccinated.
However, because the proportion of unvaccinated people is small and the NIMS population estimates are high, it makes the unvaccinated population appear significantly larger than it is. As a consequence, the Covid case rate per 100,000 unvaccinated people, when calculated using this figure, is inflated. Just being out by 1 or 2 per cent could change the apparent population of unvaccinated people by 30 per cent.
The UKHSA includes a disclaimer, telling people the data should be interpreted with “extra caution”, but Spiegelhalter said that was not good enough. Using population data from other official sources shows, instead, shows that the protection of vaccines continues.
“I cannot believe that UKHSA is putting out graphics showing higher infection rates in vaccinated than unvaccinated groups, when this is simply an artefact due to using clearly inappropriate estimates of the population,” said Spiegelhalter. “This has been repeatedly pointed out to them, and yet they continue to provide material for conspiracy theorists around the world.”
Colin Angus, a statistician from the University of Sheffield, said that there were good reasons in general to use Nims data, not least because it provides consistency across all analyses, but that in this case the UKHSA should be aware of how it is being used.
“The continued presentation of the figures is very problematic,” he said. “The warning about the huge uncertainty in the unvaccinated rates should be much clearer to avoid misinterpretation, which is clearly happening, deliberate or otherwise.”
Dr Mary Ramsay, head of immunisation at UKHSA, said: “The report clearly explains that the vaccination status of cases, inpatients and deaths should not be used to assess vaccine effectiveness and there is a high risk of misinterpreting this data because of differences in risk, behaviour and testing in the vaccinated and unvaccinated populations…Immunisation information systems like NIMS are the internationally recognised gold standard for measuring vaccine uptake.”