The Statistical Case Against Vaccine Passports

In light of yesterday’s announcement about vaccine passports at the Downing Street press briefing, I’m reposting this original piece by Dr. David Livermore, Professor of Medical Microbiology at the University of East Anglia, a member of HART, and a contributor to Collateral Global. David isn’t opposed to immigration officers demanding to see evidence that you’ve been double jabbed as a condition of entering their country. But he does draw the line at internal use of vaccine passports – as a condition of attending a pop concert, for instance. He’s done a back-of-the-envelope calculation and concluded that admitting the unvaccinated, who will soon make up no more than 10% of the population, won’t pose a major risk and in any event will be outnumbered by the vaccinated who can still transmit the disease.

Suppose a concert is attended by 1,000 people, 900 vaccinated and 100 unvaccinated, which is about the current split. Assume also that vaccines confer around 80% protection – 95% for Pfizer and Moderna and 63-76% for AZ, and that 20% of the unvaccinated are immune through prior infection.

On that basis, the audience will include 80 unvaccinated ‘vulnerables’ and 180 potential vaccine failures. In other words, unvaccinated ‘hazards’ are outnumbered 2:1 by the vaccinated ‘hazards’. ZOE app data, showing that infections in the (large) vaccinated population are beginning to outnumber those in the (small and diminishing) unvaccinated population illustrate how, nationally, we are on track to reach such ratios.

In these circumstances, excluding the unvaccinated won’t dramatically alter the risk to the audience. Rather, the good news is that 740 of the 1000 attendees ([80% x 900]+[20% x 100]) are protected by successful vaccination or prior infection and this proportion, replicated across the population outside, should give sufficient herd immunity to prevent the virus regaining traction. Moreover, it’s generally accepted that vaccination gives better than 80% protection against severe infection, meaning that the vaccinated vulnerables aren’t at much risk.

As for the 80 unvaccinated vulnerables, have we not reached the point where it is their business if they choose to hazard more severe infection? They may also smoke or drink excessively. Or, despite limited mountaineering experience, join a commercial climb of Mt Everest, as promoted by this Everest Expedition service, whose blurb includes the wonderful encouragement: “If you want to experience what it feels like to be on the highest point on the planet and have strong economic background to compensate for your old age and your fear of risks, you can sign up for the VVIP Mount Everest Expedition Service.”

The civil rights case against vaccine passports is well-known. But the statistical case – showing that they’d do very little to reduce transmission – deserves a wider audience. Worth reading in full.

Stop Press: Nightclub owners are furious with the Government about vaccine passports, according to MailOnline.

Stop Press 2: Professor Livermore has been in touch to point out how bonkers yesterday’s announcement was in light of the SAGE modelling.

Announcing – on the day that nightclubs re-open – that passports will be required two-and-a-half months hence is bizarre, however one looks at it. If they think nightclubs are such a hazard, why allow 2.5 month opening without controls? All SAGE’s modelling (below) indicates peak infections will come long before then and, for once – given that the Delta variant is clearly able to spread in summer – I think they are likely right.

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