Spectator

What the Modellers Still Don’t Understand About Herd Immunity

Bristol’s Professor Philip Thomas has a new piece in the Spectator this week. Readers may recall that I criticised his previous pieces for what seemed in my view to be wildly over-the-top predictions of the likely scale of the Delta surge.

In June, he predicted “an enormous final wave“, in which the virus “would quickly seek out the one-in-three Britons who are still susceptible: mainly the not-yet-vaccinated” and peak in the middle of July (the bit he got right) “at anywhere between two million and four million active infections“. According to the ONS, around 951,700 people in the U.K. were PCR positive in the week ending July 24th, and that appears to be the peak, which is less than half of Professor Thomas’s lower estimate.

He now admits: “The situation is better than I bargained for at the beginning of June and also better than my estimates a month later.” In fact, it’s so much better, that he thinks “the decline in active infections can only mean that England is about to reach the herd immunity threshold for the Delta variant”. By which he means that “around 86% of England’s adults and children must now be immune”. On this basis he argues that it is “extremely unlikely” that there will be a new Covid surge in the coming winter.

The problem with this analysis is it is still based on the SAGE assumption that herd immunity is a once-for-all-time thing, that was made harder to reach by the more transmissible Delta variant, but which we have now just achieved, mostly through vaccination, and it will now keep us safe.

SAGE Models Wrong Already: Hospital Occupancy is HALF What they Predict. Here’s What they Get Wrong

The models the Government is relying on to justify continuing lockdown have not got off to a good start. The projections of the huge summer wave should “freedom day” not be delayed are, as of June 21st (so before any delay could make a difference), almost twice as high for hospital occupancy as the actual number of Covid patients in hospital (see graph above).

Here’s a similar graph from the Spectator with the hospital admissions data superimposed on various SAGE projections (keep track of it here).

Fraser Nelson at the Spectator seems to share our scepticism at Lockdown Sceptics about Government modelling, reminding readers of the notorious SAGE autumn projections that envisaged up to 4,000 deaths a day by early December, but which were inaccurate the day they were published.

However, he then endorses scarcely less pessimistic modelling from Bristol University, which predicts that “hospitalisations peak at just over 900 on August 20th”.

While he admits that “no scenario points to the NHS being overwhelmed” since “Covid patients would occupy 2.5% of hospital beds” (at most), nonetheless he thinks the Government was right to delay the end of restrictions. This is because:

Britain Sees Fastest Decline in Covid Cases in the World

The Spectator has added a new table to its data hub, showing where the current level of Covid infection is in different countries around the world relative to the peak. It shows that Britain has seen the sharpest decline in the developed world, with cases now 97% lower than their peak on January 9th, 2021.

Spectator editor Fraser Nelson writes:

Britain has had one of the worst Covid death tolls in the world: today’s success should be seen in that context. The severity of the spread in UK has left higher recovery immunity even in unvaccinated age groups (almost half of under-25s have antibodies, according to the ONS) which limits the size of any third wave. UCL argues that we’ll hit herd immunity tomorrow: we discuss this in the latest edition of The Spectator’s Coffee House Shots podcast. In general, Covid is back down to (or below) summer levels and almost all of those at risk of fatal infection have been protected.

Worth reading in full.