"A major update for this week’s analysis of the UKHSA Vaccine Surveillance report, with corrections to previous data.
In our last post on week 5’s data we noted that it appeared the data for infections / hospitalisations / deaths for two doses of vaccine also included data for three doses of vaccine within two weeks of vaccination i.e., people were not counted as triple-dosed until 14 days post-jab.
As a result we tried this week to obtain further data on infections / hospitalisations / deaths that might include the missing information.
Unfortunately this was unsuccessful, but we did manage to get hold of the vaccination data used by UKHSA in its calculations (this differs from the official ‘vaccinations given’ figures because it only counts people that are still alive and resident in the country).
This new data provides some surprising additional information that necessitates revisiting prior data.
... the UKHSA has been using the number vaccinated at the end of the four week period to calculate its rates of infection / hospitalisation / death.
... (so) it’s been using a boosted population that is higher than the actual boosted population over the four-week data period.
... the estimate of the population boosted during this period should be a weighted average across the study period; this will lie somewhere within the green rectangle ...
As a result of this error, the UKHSA rates of infection / hospitalisation / death will have been smaller than they were in reality, giving the impression the vaccines were performing better than they were.
Unfortunately (this) resulted in our (prior) estimates being too pessimistic.
... this week we’ve reanalysed the data for this year using a more appropriate estimate of the proportion of the population that has received two and three doses.
As of today we’ve got data for the over-40s population, and next week we’ll aim to expand this.
... we can also estimate the vaccine effectiveness for those who only received one dose of vaccine.
... Those having taken only one dose of the vaccine appear to have approximately 50% more chance of infection compared with the unvaccinated
(note that all the values are negative, meaning the unvaccinated had lower infection rates than all the other vaccination categories).
Data for dose 2 and dose 3 of the vaccines appear to show a somewhat similar level of protection, at around minus-100%
– that is, the vaccinated appear to be approximately twice as likely to become infected with Covid as the unvaccinated.
The pronounced downward trend in the data is likely a result of the vaccines’ protection being even worse for Omicron variant.
... It’s worth mentioning that these are unadjusted vaccine effectiveness estimates of course.
The estimate for vaccine effectiveness against hospitalization:
Three doses of vaccine appear to have offered some protection against hospitalisation during the Omicron wave.
Interestingly, the data suggest that those aged 40-49 obtained the least benefit.
We hope to update this chart with data for those aged under 40 later in the week ...
Two or one dose of vaccine appears to offer very little benefit against hospitalisation.
All of the estimates of vaccine effectiveness for one dose of vaccine are slightly negative ...
... the estimates of vaccine effectiveness for two doses of vaccine are slightly positive.
Again, a pronounced downwards trend, possibly due to Omicron’s vaccine evasion.
On vaccine effectiveness against death, there is an important additional consideration. While the UKHSA data for infections and hospitalisations refer to ‘by specimen date’, the data for deaths refer to ‘by date of death’.
... the time from infection to death is usually at least 14-21 days. ...
... data for the protection offered by the vaccines against death shows a similar trend as seen in the hospitalisation data:
Three doses of vaccine appear to offer a reasonable protection against death, two doses show significantly reduced protection (especially for those aged 70-79 where it is negative), while a single dose appears to result in an increased risk of death, compared with the unvaccinated.
Again, the downward trend in the data suggests that Omicron variant has made the vaccines’ job much more difficult.
I should explain why I concentrate on ‘deaths within 60 days’ rather than the more conventional ‘deaths within 28 days’.
There is some evidence that the time course of infection in the vaccinated is more drawn out than in the unvaccinated.
... Up until now the evidence has been limited to the deaths within 28 and 60 days of infection data in the UKHSA Vaccine Surveillance report.
However, in recent weeks a new source of supporting evidence has emerged – the official deaths data published every day by the U.K. government:
An aspect of the Omicron wave I found ...
the precipitous decline in deaths has tracked the decline in cases with a lag of around 28 days (it appears to be between 25 and 31 days
... Covid deaths in fact remain elevated, but they’re not counted as Covid deaths as they’re beyond 28 days after the original infection appeared?
We should know more about this effect in the deaths data from the Vaccine Surveillance reports over the next few weeks, as they include data for deaths within 60 days of vaccination."
