Thanks chaps,
Here is a long post which I will submit because otherwise it will seem like a waste of time writing it! I knew post 5061 would open a can of worms, and I wasn't expecting to learn what I have since learned regarding the data in the vaccine surveillance reports.
I was wanting to have a discussion about this quite a while back but I left it. The reason I bring it up now is because the message in the talk I linked to in 5061 is, in summary:
Covid vaccines induce neutralizing antibodies, which are effective against the original strain.
These antibodies bind much less well to the highly mutated Omicron spike.
The vaccines also induce non-neutralizing antibodies against 'conserved' (less mutated) parts of the spike.
When the neutralizing abs are doing their job, the non-neutralizing abs cannot bind to the spike. But when the neutralizing abs stop doing their job, as with Omicron, the non-neutralizing abs can bind much more readily.
At a molecular level, when the non-neutralizing abs bind to the spike, this has the effect of forcing the spike into the 'open conformation' which enables it to bind to ACE2. Thus they enhance infection.
Thus (according to the theory) although boosters increase a person's levels of neutralizing abs, they cannot bind well to Omicron and so the non-neutralizing abs, now binding more to the spike, enhance infection.
So the thrust of the message is that vaccination against omicron is leading to antibody-dependant enhancement of
infection (not disease).
The prediction made based on the continued high circulation of the virus is that high immune pressure is now being placed on the virulence of the virus. To explain: the non-neutralizing antibodies, while enhancing infection, also prevent severe systemic disease, for example in the lung, where they suppress trans-infection of alveolar cells.
The virus needs to increase the severity of disease in order to transmit itself better in this environment of high immune pressure. So mutation that can enable a greater level of infection in the lower respiratory tract will over time be selected for, as long as the infection rate remains high.
This would lead to a severe wave of mortality.
It seems to me that this theory depends on interpreting the available data to mean that infection rates are higher in vaccinated people.
So regarding that data:
The vaccine surveillance reports say that "in order to estimate vaccine effectiveness against infection, repeat asymptomatic testing of a defined cohort of individuals is required. Studies have now reported on vaccine effectiveness against infection in healthcare workers, care home residents and the general population".
I hadn't taken this on board until you pointed it out. However, the data for cases in the general UK population still look high enough in the vaccinated groups (over 18) to be significant despite confounding factors. But let's assume that negative vaccine efficacy for people with three doses is generally
not happening.
Data is not yet available for vaccine effectiveness against Omicron after 6 months. One thing to note (see
COVID-19 vaccine surveillance report Week 16 2022, table 3) is that after 3 months, it drops to 30% for people who've had only 2 vaccine doses. Data for 4-6 months is insufficient except for Astra Zenica, which has a range of 0-35%. Data for 6+ months is insufficient.
So negative efficacy may happen for people who have not been boosted, after 6 months from their second jab. But we don't know, because most people had the booster before that time.
So for people who weren't vaccinated who survived the pre-omicron waves, they may now have at least as good protection against Omicron as those with two doses.
The question remains as to whether continually boosting the population with antibodies that were well matched for the original strain is driving the dominant circulation of immune escape variants, and whether this will ultimately lead to strains that have increased virulence.
