Infection Waves

Are Vaccines Driving the Omicron Wave?

Among the more reliable guides to the real prevalence of COVID-19 are the data collected on antibodies acquired following infection (measured as N-antibody levels, in contrast to S-antibody levels, which are acquired from both infection and vaccination).

Below is the latest graph from the UKHSA showing how antibody levels in blood donors in England have changed since autumn 2020.

From this and earlier UKHSA/PHE reports we can infer that the first wave infected around 5.7% of the population (though data from this period is mixed, with some showing up to 8.3%), the Alpha wave infected around 9.9% (perhaps a bit less if you use a higher first wave estimate – either way the first two waves together infected around 16%), the Delta wave infected around 8% and the Omicron wave has infected around 21.4% (so far). On these data, around 45% of the country have now been infected at least once at some point during the four Covid waves. Note this doesn’t allow for any waning of infection-acquired antibodies, which would mean these are lower-bound estimates.

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By Will Jones  /  11 April 2022 • 18.22
               
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The Compelling Evidence that Variants Drive Covid Surges

Recently, Anthony Brookes, a Professor of Genomics and Health Data Science at the University of Leicester, wrote a piece for the Daily Sceptic arguing that central to the virus’s surge-and-decline behaviour is the emergence of new variants, which are “able to infect (or re-infect) some fraction of individuals”.

He writes:

A series of SARS-CoV-2 variants have arisen, many of which possessed a transient selective advantage that led to a wave of infection that peaked some three-to-four months later. Several such variants have spread globally, though different successful variants have arisen simultaneously in a number of countries. The result is a three-to-four month wave pattern per country, which is also apparent globally.

The global wave pattern is shown below. It features an extended autumn and winter wave, a spring wave and a summer wave (seasons here for the northern hemisphere, of course). Note that this graph is raw positive test numbers so does not allow for increased testing.

To illustrate how this global pattern is reflected in different countries and how it relates to the emergence of new variants, I have superimposed the graph of variant proportions over time from the CoVariants website onto the positivity rate curves (the proportion of tests that come back positive, which takes into account changes in the amount of testing) from Our World in Data. I’ve done this for the 12 countries which have done the most sequencing of virus samples (according to CoVariants), plus Israel and South Africa.

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By Will Jones  /  20 September 2021 • 07.00
     
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Assembling Covid Jigsaw Pieces Into a Complete Pandemic Picture

We’re publishing an important piece today by Anthony Brookes, a Professor of Genomics and Health Data Science at the University of Leicester, in which he explains why the SARS-CoV-2 virus spreads across different populations in waves separated by three or four months. His theory is similar to that put forward by Dr Will Jones, namely, that the overall immunity levels in most populations are quite high, but need to be ‘topped up’ each time a new variant appears, causing infections to rise and then fall. Importantly, the decline in infections has little or nothing to do with non-pharmaceutical interventions – which is why daily cases started to decline before the second and third lockdowns were imposed in the U.K. and why the easing of restrictions on July 19th hasn’t caused an ‘exit wave’ – or the vaccine roll-out, since vaccines don’t appear to have much impact on infection or transmission.

Here is the abstract of Prof Brookes’s article:

  • A series of SARS-CoV-2 variants have arisen, many of which possessed a transient selective advantage that led to a wave of infection that peaked some three-to-four months later. Several such variants have spread globally, though different successful variants have arisen simultaneously in a number of countries. The result is a three-to-four month wave pattern per country, which is also apparent globally.
  • Seasonality affects variant transmissibility. Colder seasons accelerate the growth and increase the size of waves, but the continually changing environment may also differentially affect the relative transmissibility of competing variants (i.e., negatively as well as positively), thereby helping to terminate previously dominant variants and promote the growth of new ones.
  • Overall there is a minimal positive impact from quarantine policy, isolation requirements, Test and Trace regimes, social distancing, masking or other non-pharmaceutical interventions. Initially, these were the only tools in the tool-box of interventionist politicians and scientists. At best they slightly delayed the inevitable, but they also caused considerable collateral harms.
  • Immunity created by SARS-CoV-2 infection, layered on top of pre-existing immunity due to cross-immunity to other coronaviruses, provides good protection against infection, severe disease/death, and being infectious. Immunity created by vaccination also helps protect against serious disease and death, but does little or nothing to provide protection against infection or being infectious (which completely negates the case for vaccine ID cards).
  • Population immunity stems mainly from natural infections, with vaccines adding only slightly to this (and only in recent months). Population immunity is created by societal waves of infection and is somewhat variant-specific. An emerging new variant is able to infect (or re-infect) some fraction of individuals and this serves to top up and broaden the scope of our population immunity to also protect against the new variant.
  • This empirical and data-driven understanding of the pandemic allows us to make predictions. Such predictions don’t look good for some of the U.K.’s new Green List countries. But in these and all other places the ongoing arms-race between viral mutations and growing human immunity will always eventually be won by the human immune system. The virus then becomes a low-level endemic pathogen in equilibrium with its human host species. If this were not the case all humans would have been wiped out by viruses eons ago!

Worth reading in full.

By Toby Young  /  10 August 2021 • 11.34
     
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