The most striking point from this week’s UKHSA Vaccine Surveillance report – with data for the four weeks ending January 9th – is the sharp decline in unadjusted vaccine effectiveness (calculated from raw data, so not adjusted for potential confounders such as risk factors and testing behaviour) against hospitalisation (see above). The decline is particularly sharp for under-50s, with 18-29 year-olds dropping to 38% (meaning the hospitalisation rate was 38% lower among the vaccinated (two or three doses) than the unvaccinated). The sharpness of the drops coincides with the age groups with the lowest third-dose coverage (see below), which suggests it may be a waning effect accelerated by Omicron and offset by boosters.
Another possible explanation is that it is an artefact of the high number of incidental hospital admissions in recent weeks, with more than half of Covid hospital admissions being treated primarily for something else. Given vaccines offer little to no protection (or worse) against infection, they will offer the same lack of protection against incidental hospital admission as Omicron spreads in hospitals or is found in those admitted for other reasons. The difference by age may arise because infection rates in those under 50 are currently much higher than in those over 50. In truth, it is likely to be a bit of both, but without data specifically on those being treated primarily for Covid it’s difficult to get to the bottom of which is making the biggest difference.
Unadjusted vaccine effectiveness against infection continued to decline in older age groups and in under-18s this week, presumably due to the waning of the third and second doses. It is negative in all over-18s, meaning the infection rate is higher in the vaccinated than the unvaccinated; in the 18-70s it is lower than minus-100%, meaning the vaccinated are more than twice as likely to have an infection. It did however rise slightly in the 18-50s this week, from a very low base. UKHSA continues to claim this extraordinary data is a result of confounders such as different risk factors and testing behaviour between vaccinated and unvaccinated. However, the agency still has not published any data on these confounders (e.g. testing behaviour and co-morbidities by vaccination status), despite being asked repeatedly, nor made any attempt to estimate adjusted vaccine effectiveness based on this data. If you would like to ask it to do this you can email its head Mary Ramsay here (Twitter here).
Unadjusted vaccine effectiveness against death continues to hold up at high levels on this data. This suggests the data is not highly confounded by risk factors, as the UKHSA claims, as then we would see low effectiveness against death too. Note that effectiveness against death did decline until November, suggesting the third doses have helped here.
One curiosity this week is that initially the UKHSA published a mistaken version with missing data. Although it’s not clear which data was missing, Daily Sceptic reader ‘Amanuensis’ (as he’s known in the comments) has analysed it on his Substack page and thinks it may have included data just for two doses with the data for third doses missing. If so, it shows 50% more deaths in the two-dose-only group compared to the unvaccinated, which would be alarming. However, one explanation is that boosters may not be given to those at highest risk of death owing to their health condition, which would concentrate deaths in the two-dose group, artificially both lowering the effectiveness of two doses and raising the effectiveness of three doses. This is all quite speculative, however.
It’s also worth noting here the latest data from Public Health Scotland, which for two-doses-only shows negative unadjusted vaccine effectiveness (i.e., higher rates in the vaccinated than the unvaccinated) not only for reported infections but also hospitalisations and deaths. The data is so remarkable that even Herald Scotland reported on it.
Double-jabbed Scots are now more likely to be admitted to hospital with Covid than the unvaccinated amid an increase in elderly people falling ill due to waning immunity.
It comes amid “weird” data showing that case rates have been lower in unvaccinated individuals than the single, double, or even triple-jabbed since Omicron became the dominant variant in Scotland.
The counterintuitive data from Public Health Scotland (PHS) contradicts previous pandemic trends which have consistently shown infection, hospitalisation and death rates to be highest among the unvaccinated. …
According to the latest PHS report, the Covid death rate has been consistently higher since December 4th in the double-jabbed compared to the unvaccinated – but much lower in the triple-jabbed. …
In the final week of December, the death rate was 7.06 per 100,000 among the double-jabbed compared to 4.79 per 100,000 in the unvaccinated, and 0.21 per 100,000 in the triple-vaccinated.
In the week ending January 7th, the hospitalisation rate was also twice as high in the double-jabbed compared to the unvaccinated – 130 admissions per 100,000 versus 59 per 100,000 – but fell to just 15 per 100,000 in the triple-jabbed.
The admissions data does not differentiate between patients in hospital ‘because of’ Covid and those who tested positive while being treated for other ailments, but PHS said the high hospitalisation rate for double-vaccinated individuals is being driven by increasing admissions among over-70s who are not yet boosted and whose immunity is waning.
It added: “In other age groups the rates remain lower for those with two doses compared to those with one dose or unvaccinated.
“This group of individuals aged 70-plus who have had two doses of vaccine but have not yet had a booster may include some very vulnerable individuals.”
It’s interesting that PHS is pinning it on waning immunity, a stratagem which may be intended to encourage booster take-up. Though they don’t mention it, as noted above, it’s possible that the non-boosted over-70s are a higher risk group and not being boosted for that reason.
Lastly, with all this immune-evasion, there is the question of how similar Omicron really is to other variants, and whether with its reduced virulence and changed clinical profile it ought really to be deemed a new strain rather than a new variant. A recent pre-print found natural immunity down to 56% effective against re-infection, which while no worse than the reported protection from boosters (and more resilient), is still lower than you’d expect for natural immunity. The SIREN study of healthcare workers also saw a leap in reported re-infections.
One to think about.