On 12 October 2021, Alex Berenson, an American journalist appearing as a podcast guest on the Joe Rogan Experience, used data from the now replaced Public Health England (PHE) to claim that people over 40 are more likely to catch Covid-19 if they are vaccinated.
This is not true, as we have said when previous versions of the same report were misused in a similar way.
What did the podcast say?
The Joe Rogan Experience is a podcast hosted by Mr Rogan, an American comedian and former television host. It has been reported that his podcasts reach an estimated 11 million people per episode, and was the most popular podcast in the US for much of 2020 and 2021.
During the episode, Mr Berenson directed Mr Rogan to the Public Health England vaccine surveillance data covering weeks 34-37, up to 19 September this year. The two men then discussed the chart on page 13, which records the number of reported Covid cases in that period, by age and vaccination status.
Mr Berenson drew particular attention to the last two columns, showing the case rates among vaccinated and unvaccinated people of different ages. Among the over-40s, the case rates listed in the document are higher in vaccinated people.
Mr Berenson said [starting at 57mins]: “What that’s telling you is that people who are vaccinated with two doses are more likely to be infected with SARS-CoV-2 than people who are not vaccinated.”
He added: “This is UK government data, and what it says is the idea that this is a pandemic of the unvaccinated is a total lie. You are more likely to become sick if you are vaccinated than if you are not, in these older categories.”
Mr Berenson claimed that the numbers are the result of older people having weaker immune systems. However, he did not mention the footnote at the bottom of the same page, which says: “Interpretation of the case rates in vaccinated and unvaccinated population is particularly susceptible to changes in denominators and should be interpreted with extra caution.”
The previous page of the report also carries this warning: “The vaccination status of cases, inpatients and deaths is not the most appropriate method to assess vaccine effectiveness and there is a high risk of misinterpretation.”
Why Mr Berenson was wrong
It is possible that the vaccine protection against symptomatic illness may wane first among older people, who were also the first to be vaccinated.
However, as we explained in detail in our previous article, there are essentially two reasons why this data cannot be used to compare outcomes between vaccinated and unvaccinated people.
The first is that we don’t know how many unvaccinated people there are. For this, we would need to know the actual populations of each age group in England, and then subtract the vaccinated people from them.
And with vaccination rates often around 90% or higher in older age groups, the population numbers have to be very accurate, or they can skew the infection rates substantially.
In its surveillance reports, PHE (and now the UK Health Security Agency, UKHSA) uses population estimates from the National Immunisation Management System (NIMS), which are higher for the older age groups than population estimates from the Office for National Statistics. This may make Covid case rates look much lower among unvaccinated people than they really are.
The second problem is that vaccinated and unvaccinated people might also differ in other ways which could affect their chance of catching Covid. For instance, vaccinated people might feel they are less likely to catch Covid, and therefore take more risks of being exposed to it.
If so, this could make vaccinated people more “likely” to catch Covid, even though the vaccine itself is substantially protecting them.
This data needs clearer warnings
While Mr Berenson’s analysis of this data is wrong, some of the tables and charts in the PHE and UKHSA reports are easy to misinterpret, and the warnings against doing so are not easy to understand.
Apparently in response to past confusion over this data, PHE began to include the footnote on page 13 from 16 September. However, this did not prevent Mr Berenson from misunderstanding the data this month.
The vaccines do work
The effectiveness of the Covid vaccines has been assessed more accurately in other ways. At the end of August 2021, the Scientific Advisory Group for Emergencies (SAGE) gave a consensus view on the effectiveness of the Covid vaccines against symptomatic disease.
It said: “For the Delta variant, protection is assessed to be ~45% after one dose of AstraZeneca and ~55% for Pfizer. After a second dose, this increases to ~70% for AstraZeneca and ~85% for Pfizer...
“The estimate for effectiveness after a second dose of AstraZeneca has been updated to high confidence, as more robust data has become available. Effectiveness for one dose of the Moderna vaccine is assessed as ~75% with low confidence.”