Big differences in the rates between boosted and unvaccinated
It’s that time of the week when the latest UK Health Security Agency (UKHSA) COVID-19 vaccine weekly surveillance data is released.
The report has been publishing unadjusted rates of COVID-19 infection, hospitalisation and death in vaccinated and unvaccinated populations. Recently they changed the vaccinated population they were comparing from persons with at least 2 doses to persons with at least 3 doses.
In previous weeks, almost through embarrassment, the unadjusted infection rates for unvaccinated persons have been printed in a lighter font colour. This is because they were showing that, in general, the unvaccinated were much less likely to have been infected with Covid when compared with the vaccinated. This is still the case, but they have stopped trying to hide the chasm and the numbers are back in black again.
The UK’s cases have been almost exclusively Omicron since mid December so it is safe to say that all these rates concern Omicron infections or reinfections.
Let’s take a look at the rate of change in the infection numbers from last week to this week in the boosted versus the unvaccinated.
As you can see, in all age groups for the unvaccinated (except for the under 18s) there has been a drop in case rates over the last week. Similar reductions occur for both boosted and unvaccinated in all the age groups over 50. However, for the 18-49 age groups, whilst the rates are dropping in the unvaccinated, in the boosted group they are growing by between 10-20%.
Why would this be happening in these age groups? One explanation is that the over 50s had their boosters a while ago so are in the peak of their antibody production meaning they are in a similar position to the unvaccinated. However, the younger age groups have only just got boosted and so may be in a period of immunosuppression or the antibodies produced are actually facilitating infection, a form of ADE.
You can see in the graph below that the over 50s reached a high level of boosted vaccination a while ago whilst the circled under 50s is much more recent.
Hospitalisations are virtually identical to the previous week so I’ll skip them and move straight on to deaths within 28 days of a positive test.
In the younger age groups, numbers are fairly small, so rate changes will jump around a bit but in the older age groups, who have been boosted for a while, the trends should be more stable. It is quite obvious from the graph above that death rates are increasing in all age groups above 29 for the boosted and either decreasing, static or slightly increasing (70-79) in the unvaccinated.
A similar trend is occurring in the rates of change in the deaths within 60 days.
Although the rate of change is increasing in a number of unvaccinated categories, it is clear that all boosted groups (over 29) are experiencing much higher rates of change.
As the Pfizer documents showed, ADE was a major concern for them and the vaccine rollout. As this article reported, it had been observed that “a syndrome of “disease enhancement” has been reported in the past for a few viral vaccines where those immunized suffered increased severity or death when they later encountered the virus or were found to have an increased frequency of infection”.
The report stated that there is a theoretical risk of [ADE] occurring either before the full vaccine regimen is administered or in vaccinees who have waning immunity over time.
Both of these theoretical risks may be occurring right now and showing up in the data presented above.