King’s College London Professor of Genetics Tim Spector dismayed many of his Twitter followers yesterday by calling for the vaccination of older children. The reason? Because the Delta (Indian) variant means we now need 85% of the population vaccinated to reach herd immunity, he claims.
Professor Spector, who leads the ZOE Covid symptom study, was replying on Twitter to Israeli scientist Eran Segal, who tweeted: “Before Delta, Israel reached herd immunity or close to it. To regain herd immunity, we need to vaccinate as many of the 1.2 million over the age of 12 who have not yet been vaccinated.”
Spector wrote: “In the U.K. with delta we need to get near 85% of the population – which also means vaccinating older children.”
In calling for this, Prof Spector appears not to be concerned about the worries of many scientists including members of the JCVI about the benefit-versus-risk balance for teenagers in having the vaccine, or the ethics of suggesting children should be given a vaccine with no long-term safety data not for their own benefit but for the benefit of others.
The notion that a threshold of herd immunity will only be reached if 85% of the population is vaccinated also bears no relationship to real-world data. It’s not entirely clear what Segal and Spector mean by herd immunity in these tweets, but if they mean that without an 85% vaccination rate the Delta variant will continue indefinitely to cause mass hospitalisations and deaths, then perhaps they would like to explain why India’s test positivity rate entered a sustained plummet nearly two months ago, despite the Delta variant being dominant and the country at that point having only 2.5% of its population fully vaccinated? (The figure now stands scarcely higher at 4.3%.)
While there was some reduction in mobility in the country around that time, that has largely recovered now without triggering a reversal of the trend.
Plainly, the decline of India’s Delta variant outbreak did not require 85% of the population to be vaccinated. Just as the decline of England’s Alpha variant outbreak in December did not require such a measure. The Alpha variant, having declined, also failed to resurge in England as restrictions were lifted.
There is in fact no evidence from anywhere that any variant of the virus requires 85% of a population or anything like it to be vaccinated in order to exhaust itself within a few weeks. Outbreaks involving new variants quickly enter decline without vaccinating anyone let alone almost the entire population.
A further point is that we’re already now experiencing the Delta variant surge in the U.K, such as it is, so it’s too late to vaccinate children to prevent it, assuming that were possible. If the idea then becomes to vaccinate children pre-emptively for the next variant surge, in order to prevent it (again, assuming that were possible), we have to ask why? Given that all the vulnerable are fully vaccinated, why worry about teenagers getting runny noses? In fact, exposure to pathogens while young and healthy is an important part of developing a robust immune system.
The Delta variant really is no kind of reason to vaccinate children.
Stop Press: According to the ZOE app’s latest daily report, symptomatic infections in people vaccinated with at least one dose are increasing about as fast as in unvaccinated people, albeit from a lower level. While the data on vaccine effectiveness against serious illness and death has been consistently encouraging, data on effectiveness against infection has been more mixed, and this latest data suggests some of the more optimistic estimates may be on the high side.